Cmv glycoproteins and recombinant vectors

ABSTRACT

This invention also relates to recombinant vectors expressing one or more of the human CMV (HCMV) glycoproteins US2, US3, US6 and US11 or corresponding functional rhesus CMV (RhCMV) homologues Rh182, Rh184, Rh185 or Rh189, methods of making them, uses for them, expression products from them, and uses for the expression products. This invention also relates to recombinant cytomegalovirus vectors vectors lacking one or more of the glycoproteins, methods of making them, uses for them, expression products from them, and uses for the expression products.

RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

This application is a continuation of U.S. non-provisional patentapplication Ser. No. 13/626,398 filed on Sep. 25, 2012, which is acontinuation-in-part application of international patent applicationSerial No. PCT/US2011/029930 filed Mar. 25, 2011, which published as PCTPublication No. WO 2011/119920 on Sep. 29, 2011, which claims priorityto U.S. provisional patent application Ser. No. 61/317,647 filed Mar.25, 2010. Reference is made to U.S. patent application Ser. No.11/597,457 filed Apr. 28, 2008.

The foregoing applications, and all documents cited therein or duringtheir prosecution (“appln cited documents”) and all documents cited orreferenced in the appln cited documents, and all documents cited orreferenced herein (“herein cited documents”), and all documents cited orreferenced in herein cited documents, together with any manufacturer'sinstructions, descriptions, product specifications, and product sheetsfor any products mentioned herein or in any document incorporated byreference herein, are hereby incorporated herein by reference, and maybe employed in the practice of the invention. More specifically, allreferenced documents are incorporated by reference to the same extent asif each individual document was specifically and individually indicatedto be incorporated by reference.

FEDERAL FUNDING LEGEND

This invention was supported, in part, by the National Institutes ofHealth grant numbers RO1 AI059457 and RO1 AI060392), the National Centerfor Research Resources grant numbers RR016025, RR18107 and RR00163supporting the Oregon National and the Ruth L. Kirschstein NationalResearch Service Awards grant numbers T32 AI007472 and T32 HL007781. Thefederal government may have certain rights to this invention.

FIELD OF THE INVENTION

This invention relates to recombinant cytomegalovirus vectors, methodsof making them, uses for them, expression products from them, and usesfor the expression products. This invention also relates tocytomegalovirus glycoproteins US2, US3, US6 and US11, in particularrecombinant cytomegalovirus vectors lacking one or more of theglycoproteins US2, US3, US6 and US11. This invention also relates torecombinant vectors expressing one or more of the glycoproteins US2,US3, US6 and US11 of HCMV and the homologous proteins Rh182, Rh184,Rh185 and Rh189 of RhCMV.

BACKGROUND OF THE INVENTION

HCMV is an ubiquitous virus that is present in over 60% of thepopulation depending on socioeconomic status. Following primaryinfection, HCMV persists for the life span of the host. Although HCMV isgenerally benign in healthy individuals, the virus may cause devastatingdisease in immunocompromised populations resulting in high morbidity andmortality (for review, see (Pass, R. F. 2001. Cytomegalovirus, p.2675-2705. In P. M. H. David M. Knipe, Diane E. Griffin, Robert A. LambMalcolm A. Martin, Bernard Roizman and Stephen E. Straus (ed.), FieldsVirology, 4th ed. Lippincott Williams & Wilkins, Philadelphia)). Recentincreases in the number of patients undergoing immunosuppressive therapyfollowing solid organ (SOT) or allogeneic hematopoietic celltransplantation (HCT), as well as the expanded use of HCT for diseasessuch as sickle cell anemia, multiple sclerosis and solid cancers haveincreased the number of patient populations susceptible to HCMV disease(Chou, S. 1999. Transpl Infect Dis 1:105-14, Nichols, W. G., and M.Boeckh. 2000. J Clin Virol 16:25-40 and Sepkowitz, K. A. 2002. ClinInfect Dis 34:1098-107). HCMV is also the most common congenital viralinfection, and the leading infectious cause of central nervous systemmaldevelopment in neonates (Fowler, K. B. et al. 1997. J Pediatr130:624-30, Larke, R. P. et al. 1980. J Infect Dis 142:647-53 andPeckham, C. S. et al. 1983. Lancet 1:1352-5). In this regard, HCMV isconsidered the major cause of sensorineural deafness in neonatesindependent of infectious status (Fowler, K. B. et al. 1997. J Pediatr130:624-30). HCMV therefore remains a major cause of mortality inmultiple patient populations emphasizing the need for new antiviralpharmacologic and vaccine strategies. Immunity induced by naturalwild-type (WT) CMV infection has consistently been shown unable toprevent CMV re-infection (see below). This unique characteristic of CMVpresumably explains the poor efficacy of candidate vaccines in trials toprevent CMV infection (Pass, R. F. et al. 2009. N Engl J Med360:1191-9). Nevertheless, immunity to HCMV acquired through naturalinfection has been shown to significantly decrease maternal to fetaltransmission of HCMV during pregnancy. This observation would indicatethat induction of an immunity in pregnant women that is comparable tothat induced by natural CMV infection, but that is induced in a safemanner, may be able to decrease maternal to fetal transmission and havea significant impact on clinical CMV disease in the neonate.HCMV-specific T cell immunity has also been shown to afford protectionagainst CMV disease in transplant patients, presenting anotherpopulation wherein the ability to safely induce an immunity comparableto that acquired by natural CMV infection would have a clinical impacton CMV disease (Leen, A. M., and H. E. Heslop. 2008. Br J Haematol143:169-79, Riddell, S. R., and P. D. Greenberg. 2000. J AntimicrobChemother 45 Suppl T3:35-43 and Riddell, S. R. et al. 1994. Bone MarrowTransplantation 14:78-84). Cytomegalovirus is highly immunogenic, buthas evolved immune evasion mechanisms to enable virus persistence andre-infection of the sero-positive host:

The immunological resources specifically devoted to controlling HCMVinfection are enormous, with CMV being one of the most immunogenicviruses known. High antibody titers are directed against the main HCMVenvelope glycoprotein (gB) during primary infection of healthyindividuals (Alberola, J. et al. 2000. J Clin Virol 16:113-22 andRasmussen, L. et al. 1991. J Infect Dis 164:835-42), and againstmultiple viral proteins (both structural and non-structural) during MCMVinfection of mice (Farrell, H. E., and G. R. Shellam. 1989. J Gen Virol70 (Pt 10):2573-86). A large proportion of the host T cell repertoire isalso directed against CMV antigens, with 5-10 fold higher median CD4⁺ Tcell response frequencies to HCMV than to acute viruses (measles, mumps,influenza, adenovirus) or even other persistent viruses such as herpessimplex and varicella-zoster viruses (Sylwester, A. W. et al. 2005. JExp Med 202:673-85). A high frequency of CD8⁺ responses to defined HCMVepitopes or proteins is also commonly observed (Gillespie, G. M. et al.2000. J Virol 74:8140-50, Kern, F. et al. 2002. J Infect Dis185:1709-16, Kern, F. et al. 1999. Eur J Immunol 29:2908-15, Kern, F. etal. 1999. J Virol 73:8179-84 and Sylwester, A. W. et al. 2005. J Exp Med202:673-85). In a large-scale human study quantifying CD4⁺ and CD8⁺ Tcell responses to the entire HCMV genome, the mean frequencies ofCMV-specific CD4⁺ and CD8⁺ T cells exceeded 10% of the memory populationfor both subsets (Sylwester, A. W. et al. 2005. J Exp Med 202:673-85).In this study, it was not unusual for CMV-specific T cells to accountfor >25% of the memory T cell repertoire of a specific individual or atspecific tissue sites. The clinical importance of this high level ofCMV-specific immunity is most clearly shown by the occurrence ofmulti-organ CMV disease in immune-suppressed individuals duringtransplantation, and the ability of adoptive transfer of T cells toprotect these patients from CMV disease (Riddell, S. R. et al. 1994.Bone Marrow Transplantation 14:78-84).

Paradoxically, the high levels of CMV-specific immunity are unable toeither eradicate the virus from the healthy infected individual, orconfer protection of the CMV sero-positive individual againstre-infection. This ability of CMV to escape eradication by the immunesystem, and to re-infect the sero-positive host has long been believedto be linked to the multiple viral immunomodulators encoded by the virus(for review, see (Mocarski, E. S., Jr. 2002. Trends Microbiol10:332-9)). The HCMV US6 family of proteins (RhCMV homologues:Rh182-Rh189) are the most extensively studied of these immunomodulators(Loenen, W. A. et al. 2001. Semin Immunol 13:41-9). At least fourdifferent genes, US2, US3, US6 and US11—and the respective RhCMVhomologues (Rh182, Rh184, Rh185, and Rh189)—are known to interfere withassembly and transport of MHC I molecules (Ahn, K. et al. 1996. ProcNatl Acad Sci USA 93:10990-5, Ahn, K. et al. 1997. Immunity 6:613-21,Jones, T. R. et al. 1995. J Virol 69:4830-41, Pande, N. T. et al. 2005.J Virol 79:5786-98, Wiertz, E. J. et al. 1996. Cell 84:769-79 andWiertz, E. J. et al. 1996. Nature 384:432-8). Each of these fourmolecules interferes at different essential points of MHC I proteinmaturation. Briefly, US2 binds to newly synthesized heavy chain (HC) andreverse translocates the protein through the translocation channel SEC61back into the cytosol where HC is degraded by the proteasome (Wiertz, E.J. et al. 1996. Cell 84:769-79 and Wiertz, E. J. et al. 1996. Nature384:432-8). Similarly, US11 ejects MHC I back out into the cytoplasm(Wiertz, E. J. et al. 1996. Cell 84:769-). US3 and US6 act later in theMHC-I assembly process (Ahn, K. et al. 1996. Proc Natl Acad Sci USA93:10990-5 and Ahn, K. et al. 1997. Immunity 6:613-21), with US3retaining fully formed heterotrimers in the ER thus preventing theirtransport to the cell surface (Ahn, K. et al. 1996. Proc Natl Acad SciUSA 93:10990-5 and Jones, T. R. et al. 1996. PNAS USA 93:11327-33), andUS6 preventing peptide transport by TAP (and thus formation of thetrimeric complex of HC, β2m and peptide) (Ahn, K. et al. 1997. Immunity6:613-21, Hengel, H. et al. 1997. Immunity 6:623-32 and Lehner, P. J. etal. 1997. Proc Natl Acad Sci USA 94:6904-9).

Consistent with persistent replication/chronic reactivation within thehost, CMV also induces and maintains a characteristic and unique T cellimmune response. Memory T cells induced by vaccination or infection maybe broadly characterized into either effector (T_(EM)) or central(T_(CM)) memory, which follow from the distinct functions of these twomemory populations (Cheroutre, H., and L. Madakamutil. 2005. Cell MolLife Sci 62:2853-66, Mackay, C. R. et al. 1990. J Exp Med 171:801-17,Masopust, D. et al. 2001. Science 291:2413-7, Sallusto, F. et al. 1999.Nature 401:708-12 and Wherry, E. J. et al. 2003. Nat Immunol 4:225-34).T_(EM) are designed for immediate function against the invadingpathogen, being highly enriched at epithelial mucosal surfaces, arepolyfunctional expressing high levels of multiple effector cytokines(expressing TNFα, IFNγ, MIP-1β effector molecules), and have highcytotoxic potential (CD8⁺). T_(EM) and T_(CM) may also be easilydistinguished on the basis of cell surface markers, with T_(EM) beingCCR7⁻, CD28^(+/−) and T_(CM) being CCR7⁺, CD28⁺. Multiple studiesindicate that persistently replicating viruses such as CMV maintain a Tcell response that is heavily biased toward the T_(EM) phenotype (Amyes,E. et al. 2003. J Exp Med 198:903-11, Appay, V., and S. Rowland-Jones.2002. J Immunol Methods 268:9, Champagne, P. et al. 2001. Nature410:106-11, Halwani, R. et al. 2006. Springer Semin Immunopathol28:197-208 and Robinson, H. L., and R. R. Amara. 2005. Nat Med11:S25-32). Indeed, CMV is regarded as the prototypic inducer oflong-term T_(EM) (Halwani, R. et al. 2006. Springer Semin Immunopathol28:197-208, Holtappels, R. et al. 2000. Journal of Virology74:11495-503, Robinson, H. L., and R. R. Amara. 2005. Nat Med 11:S25-32and Sierro, S. et al. 2005. Eur J Immunol 35:1113-23). In contrast,analysis of T cell responses against non-persistent viruses (i.e.,influenza virus) in non-acutely infected humans, or followingimmunization with live non-persistent virus-based vaccines (YFV-17D,yellow fever vaccine, or Dryvax smallpox vaccine) shows that following ashort-lived effector T cell phenotype, long-term virus-specific memory Tcells against these non-persistent viruses is maintained primarily asT_(CM) (Lucas, M. et al. 2004. J Virol 78:7284-7 and Miller, J. D. etal. 2008. Immunity 28:710-22).

Citation or identification of any document in this application is not anadmission that such document is available as prior art to the presentinvention.

SUMMARY OF THE INVENTION

The present invention relates to relates to recombinant vectors,advantageously viral vectors that either express human cytomegalovirus(HCMV) glycoproteins US2, US3, US6 and US11 or rhesus cytomegalovirus(RCMV) glycoproteins Rh182, Rh184, Rh185 and Rh189. The invention alsorelated to HCMV vectors that have HCMV glycoproteins US2, US3, US6 andUS11 deleted therefrom.

Further objects of the invention include any or all of: to provideexpression products from such recombinants, methods for expressingproducts from such recombinants, compositions containing therecombinants or the expression products, methods for using theexpression products, methods for using the compositions, DNA from therecombinants, and methods for replicating DNA from the recombinants.

One embodiment of the invention relates to a method of superinfecting orrepeatedly an animal (including human) which may comprise (a)constructing a vector containing and expressing at least one humancytomegalovirus (HCMV) glycoprotein, wherein the glycoprotein is US2,US3, US6 or US11 (or the corresponding RhCMV homologues), and (b)administering the vector into the animal, wherein the animal might havealready been infected with the same vector.

The vector may be an adenovirus vector, adeno-associated virus (AAV)vector, alphavirus vector, herpesvirus vector (including HCMV),retrovirus vector and poxvirus vector. The vector may contain andexpress US2, US3, US6 and US11 or Rh182, Rh184, Rh185 and Rh189 or thevector may contain and express all of the glycoproteins within the US2to US11 region of HCMV or the Rh182-189 region of RhCMV

Another embodiment of the present invention relates to a method ofdetermining efficacy of a HCMV vaccine, which may comprise (a)administering a HCMV vaccine to a test subject, (b) challenging the testsubject with a HCMV vector, wherein glycoproteins within the US2 to US11region of HCMV are deleted from the HCMV vector, and (c) measuring aprotective CD8+ T cell response, wherein the HCMV vaccine is efficaciousif a CD8+ T cell response protects against challenge with the HCMVvector with the glycoproteins within the US2 to US11 region of CMVdeleted.

The US2-11 deleted HCMV vector maybe an HIV vaccine. Advantageously, theHIV antigen may be a HIV protein.

The US2-11 deleted HCMV vector may be a HCMV vaccine.

A further embodiment of the present invention relates to a method ofinducing a different CD8+ T cell response in an animal or human, whichmay comprise (a) administering a HCMV vector with at least onecytomegalovirus (CMV) glycoprotein deleted from the CMV vector, whereinthe glycoprotein is US2, US3, US6 or US11, and wherein the CMV vectorcontains and expresses at least one immunogen, and (b) administering thevector to the animal or human, wherein the CD8+ T cell response in theanimal or human differs as compared to a CMV vector that contains andexpresses the same at least one immunogen and wherein a CMV glycoproteinis not deleted from the CMV vector.

The vector may have CMV glycoproteins US2, US3, US6 and US11 deletedindividually from the CMV vector. The vector vector may also have all ofthe glycoproteins within the US2 to US11 region of CMV deleted from theCMV vector.

Accordingly, it is an object of the invention to not encompass withinthe invention any previously known product, process of making theproduct, or method of using the product such that Applicants reserve theright and hereby disclose a disclaimer of any previously known product,process, or method. It is further noted that the invention does notintend to encompass within the scope of the invention any product,process, or making of the product or method of using the product, whichdoes not meet the written description and enablement requirements of theUSPTO (35 U.S.C. §112, first paragraph) or the EPO (Article 83 of theEPC), such that Applicants reserve the right and hereby disclose adisclaimer of any previously described product, process of making theproduct, or method of using the product.

It is noted that in this disclosure and particularly in the claimsand/or paragraphs, terms such as “comprises”, “comprised”, “comprising”and the like can have the meaning attributed to it in U.S. patent law;e.g., they can mean “includes”, “included”, “including”, and the like;and that terms such as “consisting essentially of” and “consistsessentially of” have the meaning ascribed to them in U.S. patent law,e.g., they allow for elements not explicitly recited, but excludeelements that are found in the prior art or that affect a basic or novelcharacteristic of the invention.

These and other embodiments are disclosed or are obvious from andencompassed by, the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example, but notintended to limit the invention solely to the specific embodimentsdescribed, may best be understood in conjunction with the accompanyingdrawings.

FIGS. 1A-1C. CMV-infected rhesus macaques are not protected againstsuper-infection with RhCMV and superinfection of RhCMV-positive animalsis independent of viral dose. (A) At day 0, two cohorts of four RhCMV⁺animals each were infected subcutaneously with 10² or 10⁴ PFU ofRhCMV(gagL). The SIVgag-specific T cell responses in PBMC or inbronchoalveolar lavage (BAL) were monitored by flow cytometric analysisof intracellular cytokine staining (ICCS) for CD69 and tumor necrosisfactor-α (TNF-α) (S. G. Hansen et al. Science 328, 5974 (2010)) (seeFIGS. 6 and 7). (B) Day of first detection of SIVgag-expressing virus inthe urine or buccal swabs collected at the indicated intervals from eachanimal in the two cohorts shown in (A). Also included are results from athird cohort of eight RhCMV⁺ animals inoculated with 10⁷ plaque formingunits (PFU) of RhCMV(gagL). Expression of SIVgag was determined byimmunoblot using antibody to SIVgag from viral cocultures (S. G. Hansenet al. Science 328, 5974 (2010)). Each circle represents an individualanimal. (C) Long-term secretion of SIVgag-expressing virus. Urine wasisolated at the indicated days post-infection (PID) from each of theRhCMV(gagL)-infected RM, and SIVgag expression was detected fromcocultured virus by immunoblot. For control, a RhCMV-positive animalthat did not receive RhCMV(gagL) was included.

FIGS. 2A-2C. Interference with MHC-I assembly is not required forprimary infection of CMV-naïve animals. Three cohorts of two RM eachwere inoculated subcutaneously with 10⁷ PFU of recombinant ΔUS2-11(gag),ΔVIHCEΔUS2-11(gag), or RhCMV(gag). ΔUS2-11(gag) lacks the RhCMV generegion Rh182-Rh189 encoding the homologues of HCMV US2-11 (N. T. Pandeet al. J Virol 79:5786 (2005)), ΔVIHCEΔUS2-11(gag) additionally lacksthe RhCMV gene Rh178 encoding the viral inhibitor of heavy chainexpression (VIHCE) (C. J. Powers et al. PLoS Pathog 4:e1000150 (2008).(A) The RhCMV-specific T cell response in PBMC and the SIVgag-specific Tcell response in PBMC and BAL were determined at the indicated dayspost-infection using overlapping peptides to RhCMV immediate early genesIE1 and IE2 or SIVgag by flow cytometric analysis of ICCS for CD69,TNF-α, and interferon-γ (IFN-γ) (S. G. Hansen et al. Science 328, 5974(2010)) (see FIGS. 6 and 7). (B) Immunoblot of RhCMV-IE2 or SIVgagexpressed in cocultures of urine samples obtained from animals infectedwith ΔUS2-11(gag) or ΔVIHCEΔUS2-11(gag). The IE2 blot confirms that theanimals were negative for RhCMV before infection, consistent withresults from T cell assays (table 1B). (C) PCR analysis of viral genomicDNA isolated from viral cocultures at 428 days post-infection. Thepresence or absence of indicated ORFs was determined by PCR usingspecific primers (S. G. Hansen et al. Science 328, 5974 (2010)). One ofthe animals infected with RhCMV(gag) served as a control.

FIGS. 3A-3D. US2-11-deleted RhCMV is unable to superinfect RhCMV⁺ rhesusmacaques. (A) A cohort of four RhCMV⁺ RM was inoculated subcutaneouslywith 10⁷ PFU of ΔVIHCEΔUS2-11(gag) (ΔVΔU) at days 0 and 91. The CD4⁺ andCD8⁺ T cell response to SIVgag or RhCMV-IE was monitored by flowcytometric analysis of ICCS for CD69, TNF-α, and IFN-γ in PBMC. Thepercentage of the responding, specific T cells within the overall memorysubset is shown for each time point. At day 154 and again on day 224,the same cohort was inoculated with 10⁷ PFU of ΔUS2-11(gag) (ΔU), andRhCMV-IE and SIVgag-specific T cell responses were monitored bi-weekly.At day 737, the cohort was inoculated with ΔVIHCE(gag) (ΔV), and the Tcell response was monitored as before. At day 989, the cohort wasinoculated with ΔRh186-8(retanef) (ΔR). Besides SIVgag, a T cellresponse to SIVrev/nef/tat was detected by ICCS in all four animals(black lines) using corresponding overlapping peptides. (Inset) Aseparate cohort of four animals was infected with wild-type RhCMV(gag),and the RhCMV-IE and SIVgag-specific CD4⁺ and CD8⁺ T cell response wasmonitored as described above at the indicated time points for 133 days.(B) The CD4⁺ and CD8⁺ T cell response to SIVgag in BAL was measured inparallel to the PBMC T cell responses shown in (A). (C) RhCMV secretedin the urine collected from the cohort infected with RhCMV(gag), ordeletion viruses ΔVIHCEΔUS2-11(gag) or ΔUS2-11(gag), labeled ΔCMV. Viruswas isolated at the indicated days by coculture with telomerized rhesusfibroblasts (TRFs), and cell lysates were probed for expression ofSIVgag by immunoblot. (D) Expression of RhCMV-IE2, SIVgag, andSlVretanef by virus secreted in urine collected at the indicated days.Note that all animals were IE2-positive at the onset of the experiment,confirming their RhCMV-positive T cell status (Table 1D).

FIGS. 4A-4D. CD8⁺ T cells protect rhesus macaques from infection byRhCMV lacking MHC-I inhibitors. (A) Four CMV-positive RM were treated atthe indicated days with CM-T807, an antibody to CD8, before and afterinoculation with 10⁷ PFU of ΔVIHCEΔUS2-11(gag) (two animals, blacklines) or ΔUS2-11(gag) (two animals, red lines). The absolute counts ofCD8⁺ T cells in the blood of each animal are shown over time. (B) Thepresence of CD4⁺ and CD8⁺ T cell populations in PBMC of onerepresentative animal is shown for the indicated days. (C)SIVgag-specific CD4⁺ and CD8⁺ T cell responses in PBMC and BAL of CD8⁺ Tcell-depleted animals were monitored by ICCS for CD69, TNF-α, and IFN-γand are shown as a percentage of total memory CD4⁺ or CD8⁺ T cells. Notethe delayed appearance of SIVgag-specific CD8⁺ T cells. (D) Expressionof SIVgag or IE2 by RhCMV secreted in the urine of animals infected uponCD8⁺ depletion.

FIG. 5. Diagram of viruses used in Example 1. The deletion strategy isdescribed in (S. G. Hansen et al. Science 328, 5974 (2010)). Regions ofthe genome that were altered to create mutant viruses are shown indetail. All RhCMV ORFs are depicted as arrows that correspond to thedirection of the ORF within the genome. Blue arrows represent genes thatdown-regulate MHC class I. The RhCMV nomenclature is used for all ORFs(S. G. Hansen et al. J Virol 77, 6620 (2003)). For ORFs with homology toHCMV genes the name of the corresponding HCMV homologue is shown inbrackets.

FIG. 6. Response frequency gating strategy. Lymphocytes originating fromPBMC and BAL were stimulated with Ag, stained and collected on a flowcytometer as described in Example 1. Data was analyzed using ahierarchical gating strategy to delineate Ag-responding subsets. Gatesare depicted here in pink, with corresponding subset names numbered anddisplayed above the cytometric plots. For FIG. 1, response frequencieswere determined using the CD69⁺/TNFα⁺ subset (CD4⁺, cytometric plot 6a;CD8⁺, cytometric plot 8a). Response values for all other figures weredetermined using Boolean gating to delineate cells that are CD69⁺ andTNFα⁺/IFN-γ−, TNFα−/IFN-γ⁺, or TNFα⁺/IFN-γ⁺ (“Boolean Responders”; CD4₊,cytometric plot 6c; CD8⁺, cytometric plot 8c).

FIG. 7. Memory correction gating hierarchy. Cell preparations werestained and the data collected as described (C. J. Pitcher et al., JImmunol 168, 29 (2002)), followed by hierarchical analysis shown here.The pink boxes in cytometric plot 2 and 3 indicate the overall T celland T cell subset gates, respectively. The memory correction values usedfor PBMC response calculations reflect the percentage of the eventswithin the memory gate of CD4⁺ or CD8⁺ T cell-gated profiles (cytometricplots 4 and 5, respectively).

FIGS. 8A-8C. Characterization of recombinant RhCMVs in vitro. A) RT-PCR.TRFs were infected at MOI=1 with the indicated virus and total RNA washarvested at 24 hpi. cDNA was synthesized by random hexamer priming, andtranscripts were amplified with primers specific for the ORFs indicatedon the left. Genes flanking the deleted regions were included to detectpossible changes in transcription due to the deletions. WT=BACderivedwild type RhCMV. RT=reverse transcriptase. B) Expression of SIVgag byrecombinant viruses. Immunoblot analysis of FLAG-tagged SIVgag expressedby the indicated viruses. TRFs were infected at MOI=1 and total lysatewas harvested at the indicated times. Antibodies are described inExample 1. CRT=calreticulin. C) Multi-step viral growth. TRFs wereinfected at MOI=0.1 and supernatant was titered by plaque assay at theindicated times. Growth is compared to BAC-derived wild type RhCMV.

FIG. 9. Comparative genome sequencing of recombinant RhCMV. The toppanel shows the probe signal intensities for labeled genomic DNAfragments obtained from the co-hybridization of ΔVIHCEΔUS2-11(gag)(ΔVΔU, Cy5 channel, green) and BACderived RhCMV (WT, Cy3 channel, blue)to the RhCMV-DNA-microarray of overlapping oligonucleotides. Differencesin hybridization signals between the reference and test genomes areshown in red as the ratio of probe intensities for WT versusΔVIHCEΔUS2-11(gag). The second and third panels show the ratios in probeintensities for WT versus ΔUS2-11(gag) (ΔU) and WT versus ΔVIHCE(gag)(ΔV). The bottom panel shows the nucleotide numbers of the RhCMV genome,depicted in 20 kbp increments. Also indicated are the positions of theVIHCE and US2-11 deletions. Positive red spikes represent signals thatare present in the reference, but absent in the deletion viruses. Thesespikes correspond to the expected location of the deletions. Note thatsignificant differences outside the deleted regions were not observed,indicating that the genomes of the deletion viruses are identical tothat of the parental BAC in all but the deleted regions.

FIG. 10. Outcome of repeated, limiting dose, intra-rectal SIVmac239challenge of RM vaccinated with A) RhCMV vectors alone (encoding gag,retanef, pol and env; given at wks 0, 14); Group B) the same RhCMV/SIVvectors (wk 0) followed by pan-proteome Ad5 vectors (wk 14); Group C)pan-proteome DNA (wks, 0, 4, 8), followed by pan-proteome Ad5 vectors(wk 14); and Group D) unvaccinated controls (with challenge initiated atwk 59). These RM were challenged weekly until the first above-thresholdplasma viral load (>30 copies/ml) with infection considered to have beeninitiated by the challenge the prior week. The p values refer todifference in the fraction of “protected” (red) vs. progressivelyinfected (black) RM in the CMV alone and CMV/Ad5 groups vs. theunvaccinated controls). Of the 24 RM that received an RhCMV/SIV(gag/env/rev/nef/tat/pol) vector-containing regimen (Groups A and B), 13(54%) manifested initial SIVmac239 infection with a variably-sized burstof plasma viremia followed by immediate control to below detection.Although protected RM manifested low level viral blips about once every10 weeks (which gradually waned to none), overall viral control wassufficiently early and stringent to preclude any CD4+ target celldepletion, as well as to prevent induction (Group A) or boosting (GroupB) of the anti-SIVenv antibody response.

FIG. 11. No effector site CD4+ T cell depletion in protected RhCMVvector-vaccinated RM (“Controllers”). Analysis of the extent andkinetics of CD4+ memory T cell depletion in BAL following infection ofcontrollers (red) vs. non-controllers (black) within Groups A-D, withthe significance of differences in average depletion from days 21-70 piof Group A and B controllers vs. Group C determined by the Wilcoxon ranksum test.

FIG. 12. Neutralizing Ab titres against lab-adapted SIVmac251 areinduced or boosted with the onset of systemic infection in unvaccinatedcontrol RM, DNA/AD5-vaccinated RM and non-controllers in the RhCMVvector-vaccinated groups; however, controllers (red) in the lattergroups show little to no such induction or boosting, consistent withlimited Ag exposure and thus, stringent virologic control. [RP=rapidprogressor]

FIG. 13. Total SIV (gag, env, rev/nef/tat, and pol)-specific CD8+ memoryT cell responses in blood during the vaccine phase of Groups A and Bwith subsequent controllers shown in red and noncontrollers in black.Note that in both groups the peak response postboost, but not theresponse at challenge, correlated with outcome.

FIGS. 14A-14B. Peak and post-peak control and boosting responses instudy RM with progressive infection (protected RM in the CMV/CMV andCMV/Ad5 groups are not included in this figure). Note that peak andpost-peak viral suppression correlates with the ability to manifest ananamnestic CD8+ T cell response boost to infection. Quantitativereal-time RT-PCR and PCR assays targeting a highly conserved sequence inGag were used for standard measurements of plasma SIV RNA andcell-associated SIV RNA and DNA within peripheral blood and lymph nodemononuclear cells, as previously described (Cline, A. N. et al. J MedPrimatol 34, 303-312, (2005); Venneti, S. et al. Am J Pathol 172,1603-1616, (2008)).

FIG. 15. CD4+ T Cell-associated SIV in a protected RM.

FIG. 16. The “CMV/SIV Vector Shield”: CMV vectors elicit and maintainhigh frequency SIV-specific T cells in effector sites—sites that containhigh SIV target cell densities and comprise the likely sites of earlySIV amplification after mucosal inoculation. [quadrant % s shown;background was negligible for all assays.] Data are shown from thenecropsy of one animal seven years after inoculation with RhCMV(gagL).

FIG. 17. RhCMV/SIV vector-elicited SIV-specific CD8+ T cell responses donot include the typical immunodominant responses that are targeted inSIV infection itself or after vaccination with DNA and/or conventionalviral vectors. The figure shows peripheral blood CD8+ T cell responsesto a total SIVgag 15mer peptide mix (blue) or to the MamuA*01-restricted SIVgag CM9 epitope (red) in 2 representative Mamu A*01+RM, one that received RhCMV/gag twice (week 0, 14) and one that receivedRhCMV/gag at week 0 and Ad5/gag at week 14. Note that CM9 responses donot arise after RhCMV/gag vaccination, but do develop after subsequentAd5/gag vaccination.

FIG. 18. Comparison of the ability of RhCMV(gag) (wt) vs. ΔUS2-11(gag)(US2-11 KO) vectors to infect RhCMV seronegative (CMV-naïve) RM (leftpanel), RhCMV seropositive RM (middle panel), and RhCMV seropositive RMthat were depleted of CD8+ lymphocytes with mAb cM-T807 at the time ofinoculation (right panel; 100% CD8+ T cell depletion in blood for 14days). US2-11(gag) (US2-11 KO) RhCMV vectors may infect RhCMV-naïve RM,but not RhCMV+ RM, unless CD8+ T cells are depleted during the first 2weeks. Infection or lack or infection was confirmed by isolation orfailure of isolation, respectively, of the designated vector afterco-culture of urine in all cases.

FIG. 19. Comparison of CD8+ T cell epitope targeting of SIVgag-specificresponses arising after vaccination of Mamu A*01+, CMV-naïve RM with wtRhCMV(gag) vs. ΔUS2-11(gag) (US2-11 KO RhCMV(gag)) vectors. The US2-11KO vector elicits responses to all previously characterized MamuA*01-restricted gag eptiopes, whereas wt CMV vectors elicit gag-specificCD8+ T cell responses that do not target these epitopes (gag=total gag15mer mixes).

FIG. 20. Recognition of individual, consecutive gag 15mer peptides by 3each Mamu A*01+, CMV-naïve RM vaccinated with RhCMV(gag) (WT) vs.ΔUS2-11(gag) (KO) vectors. Note that whereas both wt and KO vectorselicit diverse CD8+ T cell recognition of gag epitopes, only the KOvector-elicited responses include recognition of peptides containingconventional immunodominant epitopes (yellow rectangles; epitopesdesignated at top).

FIG. 21. Antigen-specific response assays: routine staining panel.

FIG. 22. Deletion of the pp71-homologue Rh110 attenuates RhCMV in vitro.Reduced growth of RhCMV ΔRh110 and ΔRh110(retanef), but not controlRhCMV WT virus on telomerized rhesus fibroblasts (tRF). Growth isrescued by growth in pp71-expressing complementing cells (tRFs+pp71tet). Fibroblasts were infected with the indicated viruses at amultiplicity of infection (MOI) of 0.01. Culture supernatant wascollected at the indicated days and the viral titer was determined onpp71-expressing complementing cells. Multi-step growth curves showreplication deficiency of only ΔRh110 and ΔRh110(retanef), but not WTRhCMV on normal tRFs. Rescue of normal growth of ΔRh110 andΔRh110(retanef) on pp71 complementing cells (cTRF/pp71) shows thatgrowth deficiency is due to lack of pp71 expression.

FIG. 23A-23C. RhCMV ΔRh110 is attenuated in vivo and protects againstchallenge with ΔUS2-11(gag). Upper panels: Two sero-negative RM wereinoculated s.c. with 10⁷ PFU of RhCMV ΔRh110 at day 0. The CD8+ and CD4+T cell response against RhCMV lysate was measured by ICCS in PBMC andBAL at the indicated intervals. At day 231, the ΔRh110-infected animalswere challenged with 10⁷ PFU of RhCMV ΔUS2-11(gag) (ΔUgag) and the Tcell response against RhCMV lysate was measured at the indicatedintervals. The absence of a T cell boost indicates that the animals wereprotected against ΔUS2-11 challenge. Lower panels: Detection of RhCMV inurine collected at the indicated days from two RM infected withRhCMV(gag) or two RM infected with ΔRh110. Expression of SIVgag, RhCMVIE or the cellular protein GAPDH (included as loading control) wasdetermined from viral cocultures by immunoblot using specific antibodies(S. G. Hansen et al. Science 328, 5974 (2010)). The two animals infectedwith RhCMV(gag) secreted RhCMV (as shown by IE expression) because theywere CMV-positive at the onset of the experiment. At day 56, theseanimals also secreted SIVgag expressing RhCMV indicating infection. Incontrast, the two CMV-negative RM infected with ΔRh110 did not secreteRhCMV as indicated by the absence of IE-positive cocultures up to day231. This result indicates that ΔRh110 is attenuated in vivo.

FIG. 24. RhCMV lacking the tegument proteins pp65a and pp65b(ΔRh111-112) encoded by the genes Rh111 and Rh112, respectively, wascreated. Upper panel: ΔRh111-112 grows like WT RhCMV in tissue culture.Telomerized rhesus fibroblasts (tRFs) were infected with the indicatedviruses at a multiplicity of infection (MOI) of 0.01. Culturesupernatant was collected at the indicated days and the viral titer wasdetermined. Lower left panel: ΔRh110-112 induces an IE-specific, but nota pp65-specific T cell response. Two CMV-negative animals (red, green)were infected with 5×10⁶ pfu ΔRh111-112 and one animal was infected withWT RhCMV (blue) at day 0. CD8+ T cell responses to CMV were measured byintracellular cytokine staining (TNFalpha and IFNgamma) inbroncho-aveolar lavages (BAL, upper panels) or PBMC (lower panels) usingoverlapping peptides for RhCMV IE or RhCMV pp65. The panels show the % Tcell reactive to each peptide pool. Lower right panel: RhCMVΔRh111-112is secreted from infected animals. Urine was collected at 56 dayspost-infection with WT RhCMV (animals 25104 and 25546) or ΔRh111-112(animals 22037 and 23016). Expression of RhCMV IE or RhCMV pp65 wasdetermined from viral cocultures by immunoblot using specificantibodies. All animals infected with WT and ΔRh111-112 secreted RhCMVas shown by IE expression. While the virus secreted from WT-infectedanimals also expressed pp65, this was not observed for ΔRh111-112because this virus lacks the genes encoding pp65a and pp65b. Thisdemonstrates that the secreted virus corresponds to ΔRh111-112 and thatthis virus is not attenuated in vivo.

FIG. 25A-25B. RhCMV lacking pp65 protects against challenge withΔUS2-11(gag). Two animals were infected with 5×10⁶ pfu ΔRh111-112 andthe T-cell response to SIV gag (overlapping 15 mers; 4 amino acidoverlap) and T-cell response to RhCMV lysate was determined by ICCS atthe indicated days. At day 673, animals were challenged by sub-cutaneousinoculation of 10⁷ PFU of ΔUS2-11(gag) and the T cell response to RhCMVand SIVgag was measured. The absence of a boost in the RhCMV-specific Tcell response and the absence of a de novo response to SIVgag indicatesthat both animals were protected against ΔUS2-11(gag) challenge. Thisresult indicates that pp65-deleted CMV induces longterm protective Tcell responses. At day 855, animals were challenged with US2-11containing RhCMV(gag). Both animals displayed a boost in theCMV-specific T cell response and developed a de novo T cell response toSIVgag consistent with super-infection by RhCMV(gag). This resultindicates that, similar to naturally infected animals, animalsexperimentally infected with replicating recombinant CMV vaccines arenot protected against super-infection with US2-11 containing viruses.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a method of a vector capable of repeatedlyinfecting an organism which may comprise (a) constructing a vectorcontaining and expressing at least one cytomegalovirus (CMV)glycoprotein, wherein the glycoprotein is US2, US3, US6 or US11, and (b)administering the vector repeatedly into the animal or human. Wheresuperinfectivity is desired, any vector, advantageously a viral vector,may express one or more of the HCMV glycoproteins US2, US3, US6 and US11(or the RhCMV homologues Rh182, Rh184, Rh185, Rh189). Viral expressionvectors are well known to those skilled in the art and include, forexample, viruses such as adenoviruses, adeno-associated viruses (AAV),alphaviruses, herpesviruses (including cytomegalovirus itself),retroviruses and poxviruses, including avipox viruses, attenuatedpoxviruses, vaccinia viruses, and particularly, the modified vacciniaAnkara virus (MVA; ATCC Accession No. VR-1566). Such viruses, when usedas expression vectors are innately non-pathogenic in the selectedsubjects such as humans or have been modified to render themnon-pathogenic in the selected subjects. For example,replication-defective adenoviruses and alphaviruses are well known andmay be used as gene delivery vectors. Without US2-11 all of thesevectors (except for CMV which contains US2-11 naturally) elicitvector-specific immunity which prohibits their repeated use.

In an embodiment where repeated infection of a vector is desired, anyvector, advantageously a viral vector, may express one or more of theglycoproteins US2, US3, US6 and US11. In a particularly advantageousembodiment, the vector expresses glycoproteins US2, US3, US6 and US11.More advantageously, the vector contains and expresses all of theglycoproteins within the US2 to US11 region of CMV. In an advantageousembodiment, the one or more of the glycoproteins US2, US3, US6 and US11may include, but not limited to, the glycoproteins of U.S. Pat. Nos.7,892,564; 7,749,745; 7,364,893; 6,953,661; 6,913,751; 6,740,324;6,613,892; 6,410,033; 6,140,114; 6,103,531; 6,033,671; 5,908,780;5,906,935; 5,874,279; 5,853,733; 5,846,806; 5,843,458; 5,837,532;5,804,372; 5,753,476; 5,741,696; 5,731,188; 5,720,957; 5,676,952;5,599,544; 5,593,873 and 5,334,498.

In an embodiment where repeated infection of a vector is desired, anyvector, advantageously a viral vector, may express one or more of theglycoproteins RhCMV homologues Rh182, Rh184, Rh185, Rh189. In aparticularly advantageous embodiment, the vector expresses glycoproteinsRhCMV homologues Rh182, Rh184, Rh185 and Rh189. In an advantageousembodiment, the one or more of the glycoproteins Rh182, Rh184, Rh185 andRh189 may include, but not limited to, the glycoproteins of U.S. Pat.Nos. 7,635,485; 7,323,619; 6,964,762; 6,712,612; 6,544,780; 6,426,196;6,391,632; 5,858,740; 5,834,256; 5,767,250 and 5,750,106.

The present invention also encompasses a method of determining efficacyof a CMV vaccine. Currently, efficacy of CMV vaccines are difficult tomeasure because CMV easily superinfects CMV-immune individuals. Theinvention may comprise (a) administering a CMV vaccine to a testsubject, (b) challenging the test subject with a CMV vector, whereinglycoproteins within the US2 to US11 region of CMV are deleted from theCMV vector, and wherein the CMV vector contains and expresses at leastone immunogen of the CMV vaccine, and (c) measuring a CD8+ T cellresponse, wherein the CMV vaccine is efficacious if a CD8+ T cellresponse is able to prevent infection with the CMV vector lacking theglycoproteins within the US2 to US11 region of CMV and wherein the CMVvector contains and expresses at least one immunogen of the CMV vaccine.

Applicants have infected rhesus macaques with RhCMV lacking the geneRh110 that encodes for the viral transactivator pp71. RhCMVΔRh110 isgrowth-deficient in vitro and is attenuated in vitro since it is notsecreted from infected monkeys (see FIG. 22). RhCMVΔRh1110 thusrepresents an example for an attenuated CMV vaccine. Applicants testedwhether monkeys infected with RhCMVΔRh110 are protected againstchallenge with RhCMVΔUS2-11 expressing the SIV antigen Gag asimmunological marker. Protection against infection with RhCMVΔUS2-11 wasdemonstrated by the absence of a boost in RhCMV-specific T cellresponses and absence of a SIVgag-specific immune response. In contrast,monkeys infected with wildtype-virus typically show a boost of theCMV-specific T cell response and develop a de novo response to SIIVgag(see FIG. 43). This result indicates that spread-deficient, attenuatedCMV is capable of inducing a T cell response that protects againstchallenge with US2-11 deleted virus. This result also indicates that aUS2-11 deleted virus may be used to monitor the efficacy of the T cellresponse. Because of the similarities between RhCMV and HCMV, Applicantsbelieve that a CMV-vector lacking pp71 may be used as a vaccine againstCMV. Applicants further believe that a vaccine against HCMV may bevalidated by challenge with HCMV lacking US2-11.

In a similar experiment Applicants created a RhCMV lacking the tegumentproteins pp65a and pp65b encoded by the genes Rh111 and Rh112,respectively (see FIG. 24). These proteins are not required for viralgrowth in vitro or in vivo since Applicants observed thatRhCMVΔRh111-112 is secreted from infected animals However, pp65 is animmunodominant protein that is included in current formulations ofsubunit vaccines for CMV developed by various investigators. To examinewhether pp65-specific T cells are required for protection againstchallenge with ΔUS2-11, Applicants infected rhesus macaques withRhCMVΔRh111-112. As expected Applicants observed an immune responseagainst the IE-proteins of CMV, but not against pp65. In contrast, app65-specific T cell response was readily detected in animals infectedwith RhCMV (blue line). Applicants tested whether monkeys infected withRhCMVΔRh111-2 are protected against challenge with RhCMVΔUS2-11expressing the SIV antigen Gag as immunological marker. Protectionagainst infection with RhCMVΔUS2-11 was demonstrated by the absence of aboost in RhCMV-specific T cell responses and absence of aSIVgag-specific immune response (see FIG. 25). In contrast, monkeysinfected with wildtype-virus typically show a boost of the CMV-specificT cell response and develop a de novo response to SIVgag (see FIG. 25).

The present invention also relates to a method of inducing a differentCD8+ T cell response in an animal, which may comprise (a) administeringa CMV vector with at least one cytomegalovirus (CMV) glycoproteindeleted from the CMV vector, wherein the glycoprotein is US2, US3, US6or US11, and wherein the CMV vector contains and expresses at least oneimmunogen, and (b) administering the vector to the animal or human,wherein the CD8+ T cell response in the animal or human differs ascompared to a CMV vector that contains and expresses the same immunogenand wherein a CMV glycoprotein is not deleted from the CMV vector.

The present invention also relates to a method of inducing a differentpathogen-specific CD8+ T cell response in an animal, which may comprise(a) administering a CMV vector with at least one cytomegalovirus (CMV)glycoprotein deleted from the CMV vector, wherein the glycoprotein isUS2, US3, US6 or US11, and wherein the CMV vector contains and expressesat least one pathogen-derived immunogen, and (b) administering thevector to the animal, wherein the CD8+ T cell response in the animaldiffers as compared to a CMV vaccine with a CMV vector that contains andexpresses the same immunogen and wherein a CMV glycoprotein is notdeleted from the CMV vector.

Advantageously, the animal is a human.

The pathogen may be a viral pathogen and the immunogen may be a proteinderived from the viral pathogen. Viruses include, but are not limited toAdenovirus, coxsackievirus, hepatitis A virus, poliovirus, rhinovirus,Herpes simplex, type 1, Herpes simplex, type 2, Varicella-zoster virus,Epstein-barr virus, Human cytomegalovirus, Human herpesvirus, type 8,Hepatitis B virus, Hepatitis C virus, yellow fever virus, dengue virus,West Nile virus, Human immunodeficiency virus (HIV), Influenza virus,Measles virus, Mumps virus, Parainfluenza virus, Respiratory syncytialvirus, Human metapneumovirus, Human papillomavirus, Rabies virus,Rubella virus, Human bocavirus and Parvovirus B19.

The pathogen may be a bacterial pathogen and the immunogen may be aprotein derived from the bacterial pathogen. The pathogenic bacteriainclude, but are not limited to, Bordetella pertussis, Borreliaburgdorferi, Brucella abortus, Brucella canis, Brucella melitensis,Brucella suis, Campylobacter jejuni, Chlamydia pneumoniae, Chlamydiatrachomatis, Chlamydophila psittaci, Clostridium botulinum, Clostridiumdifficile, Clostridium perfringens, Clostridium tetani, Corynebacteriumdiphtheriae, Enterococcus faecalis, Enterococcus faecium, Escherichiacoli, Francisella tularensis, Haemophilus influenzae, Helicobacterpylori, Legionella pneumophila, Leptospira interrogans, Listeriamonocytogenes, Mycobacterium leprae, Mycobacterium tuberculosis,Mycobacterium ulcerans, Mycoplasma pneumoniae, Neisseria gonorrhoeae,Neisseria meningitidis, Pseudomonas aeruginosa, Rickettsia rickettsii,Salmonella typhi, Salmonella typhimurium, Shigella sonnei,Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcussaprophyticus, Streptococcus agalactiae, Streptococcus pneumoniae,Streptococcus pyogenes, Treponema pallidum, Vibrio cholera and Yersiniapestis.

The pathogen may be a parasite and the immunogen may be a proteinderived from the parasite pathogen. The parasite may be a protozoanorganism or disease caused by a protozoan organism such as, but notlimited to, Acanthamoeba, Babesiosis, Balantidiasis, Blastocystosis,Coccidia, Dientamoebiasis, Amoebiasis, Giardia, Isosporiasis,Leishmaniasis, Primary amoebic meningoencephalitis (PAM), Malaria,Rhinosporidiosis, Toxoplasmosis—Parasitic pneumonia, Trichomoniasis,Sleeping sickness and Chagas disease. The parasite may be a helminthorganism or worm or a disease caused by a helminth organism such as, butnot limted to, Ancylostomiasis/Hookworm, Anisakiasis,Roundworm—Parasitic pneumonia, Roundworm—Baylisascariasis,Tapeworm—Tapeworm infection, Clonorchiasis, Dioctophyme renalisinfection, Diphyllobothriasis—tapeworm, Guinea worm—Dracunculiasis,Echinococcosis—tapeworm, Pinworm—Enterobiasis, Liver fluke—Fasciolosis,Fasciolopsiasis—intestinal fluke, Gnathostomiasis, Hymenolepiasis, Loaboa filariasis, Calabar swellings, Mansonelliasis, Filariasis,Metagonimiasis—intestinal fluke, River blindness, Chinese Liver Fluke,Paragonimiasis, Lung Fluke, Schistosomiasis—bilharzia, bilharziosis orsnail fever (all types), intestinal schistosomiasis, urinaryschistosomiasis, Schistosomiasis by Schistosoma japonicum, Asianintestinal schistosomiasis, Sparganosis, Strongyloidiasis—Parasiticpneumonia, Beef tapeworm, Pork tapeworm, Toxocariasis, Trichinosis,Swimmer's itch, Whipworm and Elephantiasis Lymphatic filariasis. Theparasite may be an organism or disease caused by an organism such as,but not limited to, parasitic worm, Halzoun Syndrome, Myiasis, Chigoeflea, Human Botfly and Candiru. The parasite may be an ectoparasite ordisease caused by an ectoparasite such as, but not limited to, Bedbug,Head louse—Pediculosis, Body louse—Pediculosis, Crab louse—Pediculosis,Demodex—Demodicosis, Scabies, Screwworm and Cochliomyia.

The pathogen may be a cancer and the immunogen may be a protein derivedfrom the cancer. The cancers, include, but are not limited to, Acutelymphoblastic leukemia; Acute myeloid leukemia; Adrenocorticalcarcinoma; AIDS-related cancers; AIDS-related lymphoma; Anal cancer;Appendix cancer; Astrocytoma, childhood cerebellar or cerebral; Basalcell carcinoma; Bile duct cancer, extrahepatic; Bladder cancer; Bonecancer, Osteosarcoma/Malignant fibrous histiocytoma; Brainstem glioma;Brain tumor; Brain tumor, cerebellar astrocytoma; Brain tumor, cerebralastrocytoma/malignant glioma; Brain tumor, ependymoma; Brain tumor,medulloblastoma; Brain tumor, supratentorial primitive neuroectodermaltumors; Brain tumor, visual pathway and hypothalamic glioma; Breastcancer; Bronchial adenomas/carcinoids; Burkitt lymphoma; Carcinoidtumor, childhood; Carcinoid tumor, gastrointestinal; Carcinoma ofunknown primary; Central nervous system lymphoma, primary; Cerebellarastrocytoma, childhood; Cerebral astrocytoma/Malignant glioma,childhood; Cervical cancer; Childhood cancers; Chronic lymphocyticleukemia; Chronic myelogenous leukemia; Chronic myeloproliferativedisorders; Colon Cancer; Cutaneous T-cell lymphoma; Desmoplastic smallround cell tumor; Endometrial cancer; Ependymoma; Esophageal cancer;Ewing's sarcoma in the Ewing family of tumors; Extracranial germ celltumor, Childhood; Extragonadal Germ cell tumor; Extrahepatic bile ductcancer; Eye Cancer, Intraocular melanoma; Eye Cancer, Retinoblastoma;Gallbladder cancer; Gastric (Stomach) cancer; Gastrointestinal CarcinoidTumor; Gastrointestinal stromal tumor (GIST); Germ cell tumor:extracranial, extragonadal, or ovarian; Gestational trophoblastic tumor;Glioma of the brain stem; Glioma, Childhood Cerebral Astrocytoma;Glioma, Childhood Visual Pathway and Hypothalamic; Gastric carcinoid;Hairy cell leukemia; Head and neck cancer; Heart cancer; Hepatocellular(liver) cancer; Hodgkin lymphoma; Hypopharyngeal cancer; Hypothalamicand visual pathway glioma, childhood; Intraocular Melanoma; Islet CellCarcinoma (Endocrine Pancreas); Kaposi sarcoma; Kidney cancer (renalcell cancer); Laryngeal Cancer; Leukemias; Leukemia, acute lymphoblastic(also called acute lymphocytic leukemia); Leukemia, acute myeloid (alsocalled acute myelogenous leukemia); Leukemia, chronic lymphocytic (alsocalled chronic lymphocytic leukemia); Leukemia, chronic myelogenous(also called chronic myeloid leukemia); Leukemia, hairy cell; Lip andOral Cavity Cancer; Liver Cancer (Primary); Lung Cancer, Non-Small Cell;Lung Cancer, Small Cell; Lymphomas; Lymphoma, AIDS-related; Lymphoma,Burkitt; Lymphoma, cutaneous T-Cell; Lymphoma, Hodgkin; Lymphomas,Non-Hodgkin (an old classification of all lymphomas except Hodgkin's);Lymphoma, Primary Central Nervous System; Marcus Whittle, DeadlyDisease; Macroglobulinemia, Waldenström; Malignant Fibrous Histiocytomaof Bone/Osteosarcoma; Medulloblastoma, Childhood; Melanoma; Melanoma,Intraocular (Eye); Merkel Cell Carcinoma; Mesothelioma, Adult Malignant;Mesothelioma, Childhood; Metastatic Squamous Neck Cancer with OccultPrimary; Mouth Cancer; Multiple Endocrine Neoplasia Syndrome, Childhood;Multiple Myeloma/Plasma Cell Neoplasm; Mycosis Fungoides;Myelodysplastic Syndromes; Myelodysplastic/Myeloproliferative Diseases;Myelogenous Leukemia, Chronic; Myeloid Leukemia, Adult Acute; MyeloidLeukemia, Childhood Acute; Myeloma, Multiple (Cancer of theBone-Marrow); Myeloproliferative Disorders, Chronic; Nasal cavity andparanasal sinus cancer; Nasopharyngeal carcinoma; Neuroblastoma;Non-Hodgkin lymphoma; Non-small cell lung cancer; Oral Cancer;Oropharyngeal cancer; Osteosarcoma/malignant fibrous histiocytoma ofbone; Ovarian cancer; Ovarian epithelial cancer (Surfaceepithelial-stromal tumor); Ovarian germ cell tumor; Ovarian lowmalignant potential tumor; Pancreatic cancer; Pancreatic cancer, isletcell; Paranasal sinus and nasal cavity cancer; Parathyroid cancer;Penile cancer; Pharyngeal cancer; Pheochromocytoma; Pineal astrocytoma;Pineal germinoma; Pineoblastoma and supratentorial primitiveneuroectodermal tumors, childhood; Pituitary adenoma; Plasma cellneoplasia/Multiple myeloma; Pleuropulmonary blastoma; Primary centralnervous system lymphoma; Prostate cancer; Rectal cancer; Renal cellcarcinoma (kidney cancer); Renal pelvis and ureter, transitional cellcancer; Retinoblastoma; Rhabdomyosarcoma, childhood; Salivary glandcancer; Sarcoma, Ewing family of tumors; Sarcoma, Kaposi; Sarcoma, softtissue; Sarcoma, uterine; Sézary syndrome; Skin cancer (nonmelanoma);Skin cancer (melanoma); Skin carcinoma, Merkel cell; Small cell lungcancer; Small intestine cancer; Soft tissue sarcoma; Squamous cellcarcinoma—see Skin cancer (nonmelanoma); Squamous neck cancer withoccult primary, metastatic; Stomach cancer; Supratentorial primitiveneuroectodermal tumor, childhood; T-Cell lymphoma, cutaneous (MycosisFungoides and Sézary syndrome); Testicular cancer; Throat cancer;Thymoma, childhood; Thymoma and Thymic carcinoma; Thyroid cancer;Thyroid cancer, childhood; Transitional cell cancer of the renal pelvisand ureter; Trophoblastic tumor, gestational; Unknown primary site,carcinoma of, adult; Unknown primary site, cancer of, childhood; Ureterand renal pelvis, transitional cell cancer; Urethral cancer; Uterinecancer, endometrial; Uterine sarcoma; Vaginal cancer; Visual pathway andhypothalamic glioma, childhood; Vulvar cancer; Waldenströmmacroglobulinemia and Wilms tumor (kidney cancer), childhood.

Applicants demonstrate that US2-11 deleted vector may induce aqualitatively different immune response to a heterologous antigen ascompared to a recombinant wildtype virus (see FIGS. 19 and 20).Applicants inoculate animals carrying different US2-11 deleted vectorsexpressing antigens from SIV and examining T cell responses SIV antigenssuch as gag, retanef, env and pol, which are used to vaccinate CMV-naïverhesus macaques (RMs) against SIV. The T cell response is determined asindicated below.

It is an object of the invention to provide a recombinantcytomegalovirus (CMV).

It is a further object of the invention to provide such a recombinantwhich contains exogenous DNA, preferably in a non-essential region, andwhich has had one or more glycoproteins US2, US3, US6 and US11, deletedtherefrom.

It is also an object of the invention to provide such a recombinant CMVcontaining exogenous DNA.

Further objects of the invention include any or all of: to provideexpression products from such recombinants, methods for expressingproducts from such recombinants, compositions containing therecombinants or the expression products, methods for using theexpression products, methods for using the compositions, DNA from therecombinants, and methods for replicating DNA from the recombinants.

Accordingly, the invention provides a CMV synthetically modified tocontain therein exogenous DNA. The CMV advantageously has had one ormore glycoproteins US2, US3, US6 and US11, deleted therefrom.

The invention also pertains to any viral vector that contains andexpresses one or more CMV glycoproteins US2, US3, US6 and US11.

The invention further provides a vector for cloning or expression ofheterologous DNA which may comprise the recombinant CMV.

The heterologous DNA encodes an expression product which may comprise:an epitope of interest, a biological response modulator, a growthfactor, a recognition sequence, a therapeutic gene, or a fusion protein.

An epitope of interest is an antigen or immunogen or immunologicallyactive fragment thereof from a pathogen or toxin of veterinary or humaninterest.

An epitope of interest may be an antigen of pathogen or toxin, or froman antigen of a pathogen or toxin, or another antigen or toxin whichelicits a response with respect to the pathogen, of from another antigenor toxin which elicits a response with respect to the pathogen.

An epitope of interest may be an antigen of a human pathogen or toxin,or from an antigen of a human pathogen or toxin, or another antigen ortoxin which elicits a response with respect to the pathogen, or fromanother antigen or toxin which elicits a response with respect to thepathogen, such as, for instance: a Morbillivirus antigen, e.g., ameasles virus antigen such as HA or F; a rabies glycoprotein, e.g.,rabies virus glycoprotein G; an influenza antigen, e.g., influenza virusHA or N; a Herpesvirus antigen, e.g., a glycoprotein of a herpes simplexvirus (HSV), a human cytomegalovirus (HCMV), Epstein-Barr; a flavivirusantigen, a JEV, Yellow Fever virus or Dengue virus antigen; a Hepatitisvirus antigen, e.g., HBsAg; an immunodeficiency virus antigen, e.g., anHIV antigen such as gp120, gp160; a Hantaan virus antigen; a C. tetaniantigen; a mumps antigen; a pneumococcal antigen, e.g., PspA; a Borreliaantigen, e.g., OspA, OspB, OspC of Borrelia associated with Lyme diseasesuch as Borrelia burgdoreferi, Borrelia atzelli and Borrelia garinii; achicken pox (varicella zoster) antigen; or a Plasmodium antigen.

Advantageously, the epitope of interest is an immunodeficiency antigen,advantageously HIV or SIV.

Of course, the foregoing lists are intended as exemplary, as the epitopeof interest may be an antigen of any veterinary or human pathogen orfrom any antigen of any veterinary or human pathogen.

Since the heterologous DNA may be a growth factor or therapeutic gene,the recombinant CMV may be used in gene therapy. Gene therapy involvestransferring genetic information; and, with respect to gene therapy andimmunotherapy, reference is made to U.S. Pat. No. 5,252,479, which isincorporated herein by reference, together with the documents cited init and on its face, and to WO 94/16716 and U.S. application Ser. No.08/184,009, filed Jan. 19, 1994, each of which is also incorporatedherein by reference, together with the documents cited therein. Thegrowth factor or therapeutic gene, for example, may encode adisease-fighting protein, a molecule for treating cancer, a tumorsuppressor, a cytokine, a tumor associated antigen, or interferon; and,the growth factor or therapeutic gene may, for example, be selected fromthe group consisting of a gene encoding alpha-globin, beta-globin,gamma-globin, granulocyte macrophage-colony stimulating factor, tumornecrosis factor, an interleukin, macrophage colony stimulating factor,granulocyte colony stimulating factor, erythropoietin, mast cell growthfactor, tumor suppressor p53, retinoblastoma, interferon, melanomaassociated antigen or B7.

The invention still further provides an immunogenic, immunological orvaccine composition containing the recombinant CMV virus or vector, anda pharmaceutically acceptable carrier or diluent. An immunologicalcomposition containing the recombinant CMV virus or vector (or anexpression product thereof) elicits an immunological response—local orsystemic. The response may, but need not be, protective. An immunogeniccomposition containing the recombinant CMV virus or vector (or anexpression product thereof) likewise elicits a local or systemicimmunological response which may, but need not be, protective. A vaccinecomposition elicits a local or systemic protective response.Accordingly, the terms “immunological composition” and “immunogeniccomposition” include a “vaccine composition” (as the two former termsmay be protective compositions).

The invention therefore also provides a method of inducing animmunological response in a host vertebrate which may compriseadministering to the host an immunogenic, immunological or vaccinecomposition which may comprise the recombinant CMV virus or vector and apharmaceutically acceptable carrier or diluent. For purposes of thisspecification, “animal” includes all vertebrate species, except humans;and “vertebrate” includes all vertebrates, including animals (as“animal” is used herein) and humans. And, of course, a subset of“animal” is “mammal”, which for purposes of this specification includesall mammals, except humans.

The invention even further provides a therapeutic composition containingthe recombinant CMV virus or vector and a pharmaceutically acceptablecarrier or diluent. The therapeutic composition is useful in the genetherapy and immunotherapy embodiments of the invention, e.g., in amethod for transferring genetic information to an animal or human inneed of such which may comprise administering to the host thecomposition; and, the invention accordingly includes methods fortransferring genetic information.

In yet another embodiment, the invention provides a method of expressinga protein or gene product or an expression product which may compriseinfecting or transfecting a cell in vitro with a recombinant CMV virusor vector of the invention and optionally extracting, purifying orisolating the protein, gene product or expression product or DNA fromthe cell. And, the invention provides a method for cloning orreplicating a heterologous DNA sequence which may comprise infecting ortransfecting a cell in vitro or in vivo with a recombinant CMV virus orvector of the invention and optionally extracting, purifying orisolating the DNA from the cell or progeny virus

The invention in another aspect provides a method for preparing therecombinant CMV virus or vector of the invention which may compriseinserting the exogenous DNA into a non-essential region of the CMVgenome.

The method may further comprise deleting a non-essential region from theCMV genome, preferably prior to inserting the exogenous DNA.

The method may comprise in vivo recombination. Thus, the method maycomprise transfecting a cell with CMV DNA in a cell-compatible medium inthe presence of donor DNA which may comprise the exogenous DNA flankedby DNA sequences homologous with portions of the CMV genome, whereby theexogenous DNA is introduced into the genome of the CMV, and optionallythen recovering CMV modified by the in vivo recombination.

The method may also comprise cleaving CMV DNA to obtain cleaved CMV DNA,ligating the exogenous DNA to the cleaved CMV DNA to obtain hybridCMV-exogenous DNA, transfecting a cell with the hybrid CMV-exogenousDNA, and optionally then recovering CMV modified by the presence of theexogenous DNA.

Since in vivo recombination is comprehended, the invention accordinglyalso provides a plasmid which may comprise donor DNA not naturallyoccurring in CMV encoding a polypeptide foreign to CMV, the donor DNA iswithin a segment of CMV DNA which would otherwise be co-linear with anon-essential region of the CMV genome such that DNA from anon-essential region of CMV is flanking the donor DNA.

The exogenous DNA may be inserted into CMV to generate the recombinantCMV in any orientation which yields stable integration of that DNA, andexpression thereof, when desired.

The exogenous DNA in the recombinant CMV virus or vector of theinvention may include a promoter. The promoter may be from aherpesvirus. For instance, the promoter may be a cytomegalovirus (CMV)promoter, such as a human CMV (HCMV) or murine CMV promoter.

The promoter may be a truncated transcriptionally active promoter whichmay comprise a region transactivated with a transactivating proteinprovided by the virus and the minimal promoter region of the full-lengthpromoter from which the truncated transcriptionally active promoter isderived. For purposes of this specification, a “promoter” is composed ofan association of DNA sequences corresponding to the minimal promoterand upstream regulatory sequences; a “minimal promoter” is composed ofthe CAP site plus TATA box (minimum sequences for basic level oftranscription; unregulated level of transcription); and, “upstreamregulatory sequences” are composed of the upstream element(s) andenhancer sequence(s). Further, the term “truncated” indicates that thefull-length promoter is not completely present, i.e., that some portionof the full-length promoter has been removed. And, the truncatedpromoter may be derived from a herpesvirus such as MCMV or HCMV, e.g.,HCMV-IE or MCMV-IE.

Like the aforementioned promoter, the inventive promoter is preferably aherpesvirus, e.g., a MCMV or HCMV such as MCMV-IE or HCMV-IE promoter;and, there may be up to a 40% and even up to a 90% reduction in size,from a full-length promoter, based upon base pairs.

The invention thus also provides an expression cassette for insertioninto a recombinant virus or plasmid which may comprise the truncatedtranscriptionally active promoter. The expression cassette may furtherinclude a functional truncated polyadenylation signal; for instance anSV40 polyadenylation signal which is truncated, yet functional.Considering that nature provided a larger signal, it is indeedsurprising that a truncated polyadenylation signal is functional; and, atruncated polyadenylation signal addresses the insert size limitproblems of recombinant viruses such as CMV. The expression cassette mayalso include exogenous or heterologous DNA with respect to the virus orsystem into which it is inserted; and that DNA may be exogenous orheterologous DNA as described herein.

In a more specific aspect, the present invention encompasses CMV,recombinants which may comprise the HCMV-IE or MCMV-IE promoter,preferably a truncated promoter therefrom. Preferably, the HCMV-IE orMCMV-IE promoter or a truncated promoter therefrom is transactivated byCMV-induced gene products.

The invention further comprehends antibodies elicited by the inventivecompositions and/or recombinants and uses for such antibodies. Theantibodies, or the product (epitopes of interest) which elicited them,or monoclonal antibodies from the antibodies, may be used in bindingassays, tests or kits to determine the presence or absence of an antigenor antibody.

Flanking DNA used in the invention may be from the site of insertion ora portion of the genome adjacent thereto (wherein “adjacent” includescontiguous sequences, e.g., codon or codons, as well as up to as manysequences, e.g., codon or codons, before there is an interveninginsertion site).

The exogenous or heterologous DNA (or DNA foreign to CMV, or DNA notnaturally occurring in CMV) may be DNA encoding any of theaforementioned epitopes of interest, as listed above. The exogenous DNAmay include a marker, e.g., a color or light marker. The exogenous DNAmay also code for a product which would be detrimental to an insect hostsuch that the expression product may be a pesticide or insecticide. Theexogenous DNA may also code for an anti-fungal polypeptide; and, forinformation on such a polypeptide and DNA therefor, reference is made toU.S. Pat. No. 5,421,839 and the documents cited therein, incorporatedherein by reference.

The heterologous or exogenous DNA in recombinants of the inventionpreferably encodes an expression product which may comprise: an epitopeof interest, a biological response modulator, a growth factor, arecognition sequence, a therapeutic gene, or a fusion protein. Withrespect to these terms, reference is made to the following discussion,and generally to Kendrew, THE ENCYCLOPEDIA OF MOLECULAR BIOLOGY(Blackwell Science Ltd 1995) and Sambrook, Fritsch, Maniatis, MolecularCloning, A LABORATORY MANUAL (2d Edition, Cold Spring Harbor LaboratoryPress, 1989).

As to antigens for use in vaccine or immunological compositions, seealso Stedman's Medical Dictionary (24th edition, 1982, e.g., definitionof vaccine (for a list of antigens used in vaccine formulations; suchantigens or epitopes of interest from those antigens may be used in theinvention, as either an expression product of the inventive recombinantvirus, or in a multivalent composition containing an inventiverecombinant virus or an expression product therefrom).

As to epitopes of interest, one skilled in the art may determine anepitope or immunodominant region of a peptide or polypeptide and ergothe coding DNA therefor from the knowledge of the amino acid andcorresponding DNA sequences of the peptide or polypeptide, as well asfrom the nature of particular amino acids (e.g., size, charge, etc.) andthe codon dictionary, without undue experimentation.

A general method for determining which portions of a protein to use inan immunological composition focuses on the size and sequence of theantigen of interest. “In general, large proteins, because they have morepotential determinants are better antigens than small ones. The moreforeign an antigen, that is the less similar to self configurationswhich induce tolerance, the more effective it is in provoking an immuneresponse.” Ivan Roitt, Essential Immunology, 1988.

As to size: the skilled artisan may maximize the size of the proteinencoded by the DNA sequence to be inserted into the viral vector(keeping in mind the packaging limitations of the vector). To minimizethe DNA inserted while maximizing the size of the protein expressed, theDNA sequence may exclude introns (regions of a gene which aretranscribed but which are subsequently excised from the primary RNAtranscript).

At a minimum, the DNA sequence may code for a peptide at least 8 or 9amino acids long. This is the minimum length that a peptide needs to bein order to stimulate a CD4+ T cell response (which recognizes virusinfected cells or cancerous cells). A minimum peptide length of 13 to 25amino acids is useful to stimulate a CD8+ T cell response (whichrecognizes special antigen presenting cells which have engulfed thepathogen). See Kendrew, supra. However, as these are minimum lengths,these peptides are likely to generate an immunological response, i.e.,an antibody or T cell response; but, for a protective response (as froma vaccine composition), a longer peptide is preferred.

With respect to the sequence, the DNA sequence preferably encodes atleast regions of the peptide that generate an antibody response or a Tcell response. One method to determine T and B cell epitopes involvesepitope mapping. The protein of interest “is fragmented into overlappingpeptides with proteolytic enzymes. The individual peptides are thentested for their ability to bind to an antibody elicited by the nativeprotein or to induce T cell or B cell activation. This approach has beenparticularly useful in mapping T-cell epitopes since the T cellrecognizes short linear peptides complexed with MHC molecules (see FIG.20). The method is less effective for determining B-cell epitopes” sinceB cell epitopes are often not linear amino acid sequence but ratherresult from the tertiary structure of the folded three dimensionalprotein. Janis Kuby, Immunology, (1992) pp. 79-80.

Another method for determining an epitope of interest is to choose theregions of the protein that are hydrophilic. Hydrophilic residues areoften on the surface of the protein and are therefore often the regionsof the protein which are accessible to the antibody. Janis Kuby,Immunology, (1992) p. 81.

Yet another method for determining an epitope of interest is to performan X-ray crystallographic analysis of the antigen (full length)-antibodycomplex. Janis Kuby, Immunology, (1992) p. 80.

Still another method for choosing an epitope of interest which maygenerate a T cell response is to identify from the protein sequencepotential HLA anchor binding motifs which are peptide sequences whichare known to be likely to bind to the MHC molecule.

The peptide which is a putative epitope of interest, to generate a Tcell response, should be presented in a MHC complex. The peptidepreferably contains appropriate anchor motifs for binding to the MHCmolecules, and should bind with high enough affinity to generate animmune response. Factors which may be considered are: the HLA type ofthe patient (vertebrate, animal or human) expected to be immunized, thesequence of the protein, the presence of appropriate anchor motifs andthe occurrence of the peptide sequence in other vital cells.

An immune response is generated, in general, as follows: T cellsrecognize proteins only when the protein has been cleaved into smallerpeptides and is presented in a complex called the “majorhistocompatability complex MHC” located on another cell's surface. Thereare two classes of MHC complexes—class I and class II, and each class ismade up of many different alleles. Different patients have differenttypes of MHC complex alleles; they are said to have a ‘different HLAtype.

Class I MHC complexes are found on virtually every cell and presentpeptides from proteins produced inside the cell. Thus, Class I MHCcomplexes are useful for killing cells which when infected by viruses orwhich have become cancerous and as the result of expression of anoncogene. T cells which have a protein called CD8 on their surface, bindto the MHC class I cells and secrete lymphokines. The lymphokinesstimulate a response; cells arrive and kill the viral infected cell.

Class II MHC complexes are found only on antigen-presenting cells andare used to present peptides from circulating pathogens which have beenendocytosed by the antigen-presenting cells. T cells which have aprotein called CD4 bind to the MHC class II cells and kill the cell byexocytosis of lytic granules.

Some guidelines in determining whether a protein is an epitopes ofinterest which will stimulate a T cell response, include: Peptidelength—the peptide should be at least 8 or 9 amino acids long to fitinto the MHC class I complex and at least 13-25 amino acids long to fitinto a class II MCH complex. This length is a minimum for the peptide tobind to the MHC complex. It is preferred for the peptides to be longerthan these lengths because cells may cut the expressed peptides. Thepeptide should contain an appropriate anchor motif which will enable itto bind to the various class I or class II molecules with high enoughspecificity to generate an immune response (See Bocchia, M. et al,Specific Binding of Leukemia Oncogene Fusion Protein Peptides to HLAClass I Molecules, Blood 85:2680-2684; Englehard, V H, Structure ofpeptides associated with class I and class II MHC molecules Ann. Rev.Immunol. 12:181 (1994)). This may be done, without undueexperimentation, by comparing the sequence of the protein of interestwith published structures of peptides associated with the MHC molecules.Protein epitopes recognized by T cell receptors are peptides generatedby enzymatic degradation of the protein molecule and are presented onthe cell surface in association with class I or class II MHC molecules.

Further, the skilled artisan may ascertain an epitope of interest bycomparing the protein sequence with sequences listed in the protein database. Regions of the protein which share little or no homology arebetter choices for being an epitope of that protein and are thereforeuseful in a vaccine or immunological composition. Regions which sharegreat homology with widely found sequences present in vital cells shouldbe avoided.

Even further, another method is simply to generate or express portionsof a protein of interest, generate monoclonal antibodies to thoseportions of the protein of interest, and then ascertain whether thoseantibodies inhibit growth in vitro of the pathogen from which the fromwhich the protein was derived. The skilled artisan may use the otherguidelines set forth in this disclosure and in the art for generating orexpressing portions of a protein of interest for analysis as to whetherantibodies thereto inhibit growth in vitro. For example, the skilledartisan may generate portions of a protein of interest by: selecting 8to 9 or 13 to 25 amino acid length portions of the protein, selectinghydrophilic regions, selecting portions shown to bind from X-ray data ofthe antigen (full length)-antibody complex, selecting regions whichdiffer in sequence from other proteins, selecting potential HLA anchorbinding motifs, or any combination of these methods or other methodsknown in the art.

Epitopes recognized by antibodies are expressed on the surface of aprotein. To determine the regions of a protein most likely to stimulatean antibody response one skilled in the art may preferably perform anepitope map, using the general methods described above, or other mappingmethods known in the art.

As may be seen from the foregoing, without undue experimentation, fromthis disclosure and the knowledge in the art, the skilled artisan mayascertain the amino acid and corresponding DNA sequence of an epitope ofinterest for obtaining a T cell, B cell and/or antibody response. Inaddition, reference is made to Gefter et al., U.S. Pat. No. 5,019,384,issued May 28, 1991, and the documents it cites, incorporated herein byreference (Note especially the “Relevant Literature” section of thispatent, and column 13 of this patent which discloses that: “A largenumber of epitopes have been defined for a wide variety of organisms ofinterest. Of particular interest are those epitopes to whichneutralizing antibodies are directed.

With respect to expression of a biological response modulator, referenceis made to Wohlstadter, “Selection Methods,” WO 93/19170, published Sep.30, 1993, and the documents cited therein, incorporated herein byreference.

For instance, a biological response modulator modulates biologicalactivity; for instance, a biological response modulator is a modulatorycomponent such as a high molecular weight protein associated withnon-NMDA excitatory amino acid receptors and which allostericallyregulates affinity of AMPA binding (See Kendrew, supra). The recombinantof the present invention may express such a high molecular weightprotein.

More generally, nature has provided a number of precedents of biologicalresponse modulators. Modulation of activity may be carried out throughmechanisms as complicated and intricate as allosteric induced quaternarychange to simple presence/absence, e.g., expression/degradation,systems. Indeed, the repression/activation of expression of manybiological molecules is itself mediated by molecules whose activitiesare capable of being modulated through a variety of mechanisms.

Table 2 of Neidhardt et al Physiology of the Bacterial Cell (SinauerAssociates Inc., Publishers, 1990), at page 73, lists chemicalmodifications to bacterial proteins. As is noted in that table, somemodifications are involved in proper assembly and other modificationsare not, but in either case such modifications are capable of causingmodulation of function. From that table, analogous chemical modulationsfor proteins of other cells may be determined, without undueexperimentation.

In some instances modulation of biological functions may be mediatedsimply through the proper/improper localization of a molecule. Moleculesmay function to provide a growth advantage or disadvantage only if theyare targeted to a particular location. For example, a molecule may betypically not taken up or used by a cell, as a function of that moleculebeing first degraded by the cell by secretion of an enzyme for thatdegradation. Thus, production of the enzyme by a recombinant mayregulate use or uptake of the molecule by a cell. Likewise, therecombinant may express a molecule which binds to the enzyme necessaryfor uptake or use of a molecule, thereby similarly regulating its uptakeor use.

Localization targeting of proteins carried out through cleavage ofsignal peptides another type of modulation or regulation. In this case,a specific endoprotease catalytic activity may be expressed by therecombinant.

Other examples of mechanisms through which modulation of function mayoccur are RNA virus poly-proteins, allosteric effects, and generalcovalent and non-covalent steric hindrance. HIV is a well studiedexample of an RNA virus which expresses non-functional poly-proteinconstructs. In HIV “the gag, pol, and env poly-proteins are processed toyield, respectively, the viral structural proteins p17, p24, andp15-reverse transcriptase and integrase—and the two envelope proteinsgp41 and gp120” (Kohl et al., PNAS USA 85:4686-90 (1988)). The propercleavage of the poly-proteins is crucial for replication of the virus,and virions carrying inactive mutant HIV protease are non-infectious.This is another example of the fusion of proteins down-modulating theiractivity. Thus, it is possible to construct recombinant viruses whichexpress molecules which interfere with endoproteases, or which provideendoproteases, for inhibiting or enhancing the natural expression ofcertain proteins (by interfering with or enhancing cleavage).

The functional usefulness of enzymes may also be modulated by alteringtheir capability of catalyzing a reaction. Illustrative examples ofmodulated molecules are zymogens, formation/disassociation ofmulti-subunit functional complexes, RNA virus poly-protein chains,allosteric interactions, general steric hindrance (covalent andnon-covalent) and a variety of chemical modifications such asphosphorylation, methylation, acetylation, adenylation, anduridenylation (see Table 1 of Neidhardt, supra, at page 315 and Table 2at page 73).

Zymogens are examples of naturally occurring protein fusions which causemodulation of enzymatic activity. Zymogens are one class of proteinswhich are converted into their active state through limited proteolysis.See Table 3 of Reich, Proteases and Biological Control, Vol. 2, (1975)at page 54). Nature has developed a mechanism of down-modulating theactivity of certain enzymes, such as trypsin, by expressing theseenzymes with additional “leader” peptide sequences at their aminotermini. With the extra peptide sequence the enzyme is in the inactivezymogen state. Upon cleavage of this sequence the zymogen is convertedto its enzymatically active state. The overall reaction rates of thezymogen are “about 10.sup.5-10.sup.6 times lower than those of thecorresponding enzyme” (See Table 3 of Reich, supra at page 54).

It is therefore possible to down-modulate the function of certainenzymes simply by the addition of a peptide sequence to one of itstermini. For example, with knowledge of this property, a recombinant mayexpress peptide sequences containing additional amino acids at one orboth terminii.

The formation or disassociation of multi-subunit enzymes is another waythrough which modulation may occur. Different mechanisms may beresponsible for the modulation of activity upon formation ordisassociation of multi-subunit enzymes.

Therefore, sterically hindering the proper specific subunit interactionswill down-modulate the catalytic activity. And accordingly, therecombinant of the invention may express a molecule which stericallyhinders a naturally occurring enzyme or enzyme complex, so as tomodulate biological functions.

Certain enzyme inhibitors afford good examples of functionaldown-modulation through covalent steric hindrance or modification.Suicide substrates which irreversibly bind to the active site of anenzyme at a catalytically important amino acid in the active site areexamples of covalent modifications which sterically block the enzymaticactive site. An example of a suicide substrate is TPCK for chymotrypsin(Fritsch, Enzyme Structure and Mechanism, 2d ed; Freeman & Co.Publishers, 1984)). This type of modulation is possible by therecombinant expressing a suitable suicide substrate, to thereby modulatebiological responses (e.g., by limiting enzyme activity).

There are also examples of non-covalent steric hindrance including manyrepressor molecules. The recombinant may express repressor moleculeswhich are capable of sterically hindering and thus down-modulating thefunction of a DNA sequence by preventing particular DNA-RNA polymeraseinteractions.

Allosteric effects are another way through which modulation is carriedout in some biological systems. Aspartate transcarbamoylase is a wellcharacterized allosteric enzyme. Interacting with the catalytic subunitsare regulatory domains. Upon binding to CTP or UTP the regulatorysubunits are capable of inducing a quaternary structural change in theholoenzyme causing down-modulation of catalytic activity. In contrast,binding of ATP to the regulatory subunits is capable of causingup-modulation of catalytic activity (Fritsch, supra). Using methods ofthe invention, molecules may be expressed which are capable of bindingand causing modulatory quaternary or tertiary changes.

In addition, a variety of chemical modifications, e.g., phosphorylation,methylation, acetylation, adenylation, and uridenylation may be carriedout so as to modulate function. It is known that modifications such asthese play important roles in the regulation of many important cellularcomponents. Table 2 of Neidhardt, supra, at page 73, lists differentbacterial enzymes which undergo such modifications. From that list, oneskilled in the art may ascertain other enzymes of other systems whichundergo the same or similar modifications, without undueexperimentation. In addition, many proteins which are implicated inhuman disease also undergo such chemical modifications. For example,many oncogenes have been found to be modified by phosphorylation or tomodify other proteins through phosphorylation or dephosphorylation.Therefore, the ability afforded by the invention to express modulatorswhich may modify or alter function, e.g., phosphorylation, is ofimportance.

From the foregoing, the skilled artisan may use the present invention toexpress a biological response modulator, without any undueexperimentation.

With respect to expression of fusion proteins by inventive recombinants,reference is made to Sambrook, Fritsch, Maniatis, Molecular Cloning, ALABORATORY MANUAL (2d Edition, Cold Spring Harbor Laboratory Press,1989) (especially Volume 3), and Kendrew, supra, incorporated herein byreference. The teachings of Sambrook et al., may be suitably modified,without undue experimentation, from this disclosure, for the skilledartisan to generate recombinants expressing fusion proteins.

With regard to gene therapy and immunotherapy, reference is made to U.S.Pat. Nos. 4,690,915 and 5,252,479, which are incorporated herein byreference, together with the documents cited therein it and on theirface, and to WO 94/16716 and U.S. application Ser. No. 08/184,009, filedJan. 19, 1994, each of which is also incorporated herein by reference,together with the documents cited therein.

A growth factor may be defined as multifunctional, locally actingintercellular signalling peptides which control both ontogeny andmaintenance of tissue and function (see Kendrew, especially at page 455et seq.).

The growth factor or therapeutic gene, for example, may encode adisease-fighting protein, a molecule for treating cancer, a tumorsuppressor, a cytokine, a tumor associated antigen, or interferon; and,the growth factor or therapeutic gene may, for example, be selected fromthe group consisting of a gene encoding alpha-globin, beta-globin,gamma-globin, granulocyte macrophage-colony stimulating factor, tumornecrosis factor, an interleukin (e.g., an interleukin selected frominterleukins 1 to 14, or 1 to 11, or any combination thereof),macrophage colony stimulating factor, granulocyte colony stimulatingfactor, erythropoietin, mast cell growth factor, tumor suppressor p53,retinoblastoma, interferon, melanoma associated antigen or B7. U.S. Pat.No. 5,252,479 provides a list of proteins which may be expressed in anadenovirus system for gene therapy, and the skilled artisan is directedto that disclosure. WO 94/16716 and U.S. application Ser. No.08/184,009, filed Jan. 19, 1994, provide genes for cytokines and tumorassociated antigens and immunotherapy methods, including ex vivomethods, and the skilled artisan is directed to those disclosures.

Thus, one skilled in the art may create recombinants expressing a growthfactor or therapeutic gene and use the recombinants, from thisdisclosure and the knowledge in the art, without undue experimentation.

Moreover, from the foregoing and the knowledge in the art, no undueexperimentation is required for the skilled artisan to construct aninventive recombinant which expresses an epitope of interest, abiological response modulator, a growth factor, a recognition sequence,a therapeutic gene, or a fusion protein; or for the skilled artisan touse such a recombinant.

It is noted that the exogenous or heterologous DNA may itself include apromoter for driving expression in the recombinant CMV, or the exogenousDNA may simply be coding DNA and appropriately placed downstream from anendogenous promoter to drive expression. Further, multiple copies ofcoding DNA or use of a strong or early promoter or early and latepromoter, or any combination thereof, may be done so as to amplify orincrease expression. Thus, the exogenous or heterologous DNA may besuitably positioned with respect to an endogenous promoter like the E3or the MLP promoters, or those promoters may be translocated to beinserted at another location, with the exogenous or heterologous DNA.The coding DNA may be DNA coding for more than one protein so as to haveexpression of more than one product from the recombinant CMV.

The expression products may be antigens, immunogens or epitopes ofinterest; and therefore, the invention further relates to immunological,antigenic or vaccine compositions containing the expression products.Further, since the CMV vector, in certain instances, may be administereddirectly to a suitable host, the invention relates to compositionscontaining the CMV vector. Additionally, since the expression productmay be isolated from the CMV vector in vitro or from cells infected ortransfected by the CMV vector in vitro, the invention relates to methodsfor expressing a product, e.g., which may comprise inserting theexogenous DNA into a CMV as a vector, e.g., by restriction/ligation orby recombination followed by infection or transfection of suitable cellsin vitro with a recombinant CMV, and optionally extracting, purifying orisolating the expression product from the cells. Any suitableextraction, purification or isolation techniques may be employed.

In particular, after infecting cells with the recombinant CMV, theprotein(s) from the expression of the exogenous DNA are collected byknown techniques such as chromatography (see Robbins, EPA 0162738A1;Panicali, EPA 0261940A2); Richardson, supra; Smith et al., supra;Pennock et al., supra; EP Patent Publication No. 0265785). The collectedprotein(s) may then be employed in a vaccine, antigenic or immunologicalcomposition which also contains a suitable carrier.

Thus, the recombinant CMV may be used to prepare proteins such asantigens, immunogens, epitopes of interest, etc. which may be furtherused in immunological, antigenic or vaccine compositions. It is notedthat a recombinant CMV expressing a product detrimental to growth ordevelopment of insects may be used to prepare an insecticide, and arecombinant CMV expressing a product detrimental to growth of plants maybe used to prepare a herbicide (by isolating the expression product andadmixing it with an insecticidally or herbicidally acceptable carrier ordiluent) and a recombinant CMV expressing an anti-fungal polypeptide maybe used to prepare an anti-fungal preparation (by isolating theexpression product and admixing it with a suitable carrier or diluent).

As the expression products may provide an antigenic, immunological orprotective (vaccine) response, the invention further relates to productstherefrom; namely, antibodies and uses thereof. More in particular, theexpression products may elicit antibodies. The antibodies may be formedinto monoclonal antibodies; and, the antibodies or expression productsmay be used in kits, assays, tests, and the like involving binding, sothat the invention relates to these uses too. Additionally, since therecombinants of the invention may be used to replicate DNA, theinvention relates to recombinant CMV as a vector and methods forreplicating DNA by infecting or transfecting cells with the recombinantand harvesting DNA therefrom. The resultant DNA may be used as probes orprimers or for amplification.

The administration procedure for recombinant CMV or expression productthereof, compositions of the invention such as immunological, antigenicor vaccine compositions or therapeutic compositions may be via aparenteral route (intradermal, intramuscular or subcutaneous). Such anadministration enables a systemic immune response. The administrationmay be via a mucosal route, e.g., oral, nasal, genital, etc. Such anadministration enables a local immune response.

More generally, the inventive antigenic, immunological or vaccinecompositions or therapeutic compositions (compositions containing theCMV recombinants of the invention or expression products) may beprepared in accordance with standard techniques well known to thoseskilled in the pharmaceutical arts. Such compositions may beadministered in dosages and by techniques well known to those skilled inthe medical arts taking into consideration such factors as the breed orspecies, age, sex, weight, and condition of the particular patient, andthe route of administration. The compositions may be administered alone,or may be co-administered or sequentially administered with othercompositions of the invention or with other immunological, antigenic orvaccine or therapeutic compositions. Such other compositions may includepurified native antigens or epitopes or antigens or epitopes from theexpression by a recombinant CMV or another vector system; and areadministered taking into account the aforementioned factors.

Examples of compositions of the invention include liquid preparationsfor orifice, e.g., oral, nasal, anal, genital, e.g., vaginal, etc.,administration such as suspensions, syrups or elixirs; and, preparationsfor parenteral, subcutaneous, intradermal, intramuscular or intravenousadministration (e.g., injectable administration) such as sterilesuspensions or emulsions. In such compositions the recombinant may be inadmixture with a suitable carrier, diluent, or excipient such as sterilewater, physiological saline, glucose or the like.

Antigenic, immunological or vaccine compositions typically may containan adjuvant and an amount of the recombinant CMV or expression productto elicit the desired response. In human applications, alum (aluminumphosphate or aluminum hydroxide) is a typical adjuvant. Saponin and itspurified component Quil A, Freund's complete adjuvant and otheradjuvants used in research and veterinary applications have toxicitieswhich limit their potential use in human vaccines. Chemically definedpreparations such as muramyl dipeptide, monophosphoryl lipid A,phospholipid conjugates such as those described by Goodman-Snitkoff etal. J. Immunol. 147:410-415 (1991) and incorporated by reference herein,encapsulation of the protein within a proteoliposome as described byMiller et al., J. Exp. Med. 176:1739-1744 (1992) and incorporated byreference herein, and encapsulation of the protein in lipid vesiclessuch as Novasome lipid vesicles (Micro Vescular Systems, Inc., Nashua,N.H.) may also be used.

The composition may be packaged in a single dosage form for immunizationby parenteral (i.e., intramuscular, intradermal or subcutaneous)administration or orifice administration, e.g., perlingual (i.e., oral),intragastric, mucosal including intraoral, intraanal, intravaginal, andthe like administration. And again, the effective dosage and route ofadministration are determined by the nature of the composition, by thenature of the expression product, by expression level if recombinant CMVis directly used, and by known factors, such as breed or species, age,sex, weight, condition and nature of host, as well as LD₅₀ and otherscreening procedures which are known and do not require undueexperimentation. Dosages of expressed product may range from a few to afew hundred micrograms, e.g., 5 to 500 μg. The inventive recombinant maybe administered in any suitable amount to achieve expression at thesedosage levels. The vaccinal CMV is administered in an amount of about10^(3.5) pfu; thus, the inventive recombinant is preferably administeredin at least this amount; more preferably about 10⁴ pfu to about 10⁶ pfu.Other suitable carriers or diluents may be water or a buffered saline,with or without a preservative. The expression product or recombinantCMV may be lyophilized for resuspension at the time of administration ormay be in solution.

The carrier may also be a polymeric delayed release system. Syntheticpolymers are particularly useful in the formulation of a compositionhaving controlled release. An early example of this was thepolymerization of methyl methacrylate into spheres having diameters lessthan one micron to form so-called nano particles, reported by Kreuter,J., Microcapsules and Nanoparticles in Medicine and Pharmacology, M.Donbrow (Ed). CRC Press, p. 125-148.

Microencapsulation has been applied to the injection ofmicroencapsulated pharmaceuticals to give a controlled release. A numberof factors contribute to the selection of a particular polymer formicroencapsulation. The reproducibility of polymer synthesis and themicroencapsulation process, the cost of the microencapsulation materialsand process, the toxicological profile, the requirements for variablerelease kinetics and the physicochemical compatibility of the polymerand the antigens are all factors that must be considered. Examples ofuseful polymers are polycarbonates, polyesters, polyurethanes,polyorthoesters and polyamides, particularly those that arebiodegradable.

A frequent choice of a carrier for pharmaceuticals and more recently forantigens is poly(d,l-lactide-co-glycolide) (PLGA). This is abiodegradable polyester that has a long history of medical use inerodible sutures, bone plates and other temporary prostheses where ithas not exhibited any toxicity. A wide variety of pharmaceuticalsincluding peptides and antigens have been formulated into PLGAmicrocapsules. A body of data has accumulated on the adaption of PLGAfor the controlled release of antigen, for example, as reviewed byEldridge, J. H., et al. Current Topics in Microbiology and Immunology.1989, 146:59-66. The entrapment of antigens in PLGA microspheres of 1 to10 microns in diameter has been shown to have a remarkable adjuvanteffect when administered orally. The PLGA microencapsulation processuses a phase separation of a water-in-oil emulsion. The compound ofinterest is prepared as an aqueous solution and the PLGA is dissolved ina suitable organic solvents such as methylene chloride and ethylacetate. These two immiscible solutions are co-emulsified by high-speedstirring. A non-solvent for the polymer is then added, causingprecipitation of the polymer around the aqueous droplets to formembryonic microcapsules. The microcapsules are collected, and stabilizedwith one of an assortment of agents (polyvinyl alcohol (PVA), gelatin,alginates, polyvinylpyrrolidone (PVP), methyl cellulose) and the solventremoved by either drying in vacuo or solvent extraction.

Thus, solid, including solid-containing-liquid, liquid, and gel(including “gel caps”) compositions are envisioned.

Additionally, the inventive vectors, e.g., recombinant CMV, and theexpression products therefrom may stimulate an immune or antibodyresponse in animals. From those antibodies, by techniques well-known inthe art, monoclonal antibodies may be prepared and, those monoclonalantibodies, may be employed in well known antibody binding assays,diagnostic kits or tests to determine the presence or absence ofantigen(s) and therefrom the presence or absence of the naturalcausative agent of the antigen or, to determine whether an immuneresponse to that agent or to the antigen(s) has simply been stimulated.

Monoclonal antibodies are immunoglobulin produced by hybridoma cells. Amonoclonal antibody reacts with a single antigenic determinant andprovides greater specificity than a conventional, serum-derivedantibody. Furthermore, screening a large number of monoclonal antibodiesmakes it possible to select an individual antibody with desiredspecificity, avidity and isotype. Hybridoma cell lines provide aconstant, inexpensive source of chemically identical antibodies andpreparations of such antibodies may be easily standardized. Methods forproducing monoclonal antibodies are well known to those of ordinaryskill in the art, e.g., Koprowski, H. et al., U.S. Pat. No. 4,196,265,issued Apr. 1, 1989, incorporated herein by reference.

Uses of monoclonal antibodies are known. One such use is in diagnosticmethods, e.g., David, G. and Greene, H., U.S. Pat. No. 4,376,110, issuedMar. 8, 1983, incorporated herein by reference.

Monoclonal antibodies have also been used to recover materials byimmunoadsorption chromatography, e.g. Milstein, C., 1980, ScientificAmerican 243:66, 70, incorporated herein by reference.

Furthermore, the inventive recombinant CMV or expression productstherefrom may be used to stimulate a response in cells in vitro or exvivo for subsequent reinfusion into a patient. If the patient isseronegative, the reinfusion is to stimulate an immune response, e.g.,an immunological or antigenic response such as active immunization. In aseropositive individual, the reinfusion is to stimulate or boost theimmune system against a pathogen.

The recombinant CMV of the invention are also useful for generating DNAfor probes or for PCR primers which may be used to detect the presenceor absence of hybridizable DNA or to amplify DNA, e.g., to detect apathogen in a sample or for amplifying DNA.

Furthermore, as discussed above, the invention comprehends promoters andexpression cassettes which are useful in adenovirus systems, as well asin any viral or cell system which provides a transactivating protein.

The expression cassette of the invention may further include afunctional truncated polyadenylation signal; for instance an SV40polyadenylation signal which is truncated, yet functional. Theexpression cassette may contain exogenous or heterologous DNA (withrespect to the virus or system into which the promoter or expressioncassette is being inserted); for instance exogenous or heterologouscoding DNA as herein described above, and in the Examples. This DNA maybe suitably positioned and operably linked to the promoter forexpression. The expression cassette may be inserted in any orientation;preferably the orientation which obtains maximum expression from thesystem or virus into which the expression cassette is inserted.

While the promoter and expression cassette are specifically exemplifiedwith reference to adenoviruses, the skilled artisan may adapt theseembodiments of the invention to other viruses and to plasmids for cellssuch as eukaryotic cells, without undue experimentation, by simplyascertaining whether the virus, plasmid, cell or system provides thetransactivating protein.

As to HCMV promoters, reference is made to U.S. Pat. Nos. 5,168,062 and5,385,839, incorporated herein by reference. As to transfecting cellswith plasmid DNA for expression therefrom, reference is made to Felgneret al. (1994), J. Biol. Chem. 269, 2550-2561, incorporated herein byreference. And, as to direct injection of plasmid DNA as a simple andeffective method of vaccination against a variety of infectious diseasesreference is made to Science, 259:1745-49, 1993, incorporated herein byreference. It is therefore within the scope of this invention that theinventive promoter and expression cassette be used in systems other thanadenovirus; for example, in plasmids for the direct injection of plasmidDNA.

The protein fragments of the present invention form a further aspect ofthe invention; and, such compounds may be used in methods of medicaltreatments, such as for diagnosis, preventing or treating HIV or foreliciting antibodies for diagnosis of HIV, including use in vaccines.Further, such compounds may be used in the preparation of medicamentsfor such treatments or prevention, or compositions for diagnosticpurposes. The compounds may be employed alone or in combination withother treatments, vaccines or preventatives; and, the compounds may beused in the preparation of combination medicaments for such treatmentsor prevention, or in kits containing the compound and the othertreatment or preventative.

In yet another embodiment, the present invention also encompassed theuse of the protein fragments of the present invention described hereinas immunogens, advantageously as HIV-1 vaccine components.

The terms “protein”, “peptide”, “polypeptide”, and “amino acid sequence”are used interchangeably herein to refer to polymers of amino acidresidues of any length. The polymer may be linear or branched, it maycomprise modified amino acids or amino acid analogs, and it may beinterrupted by chemical moieties other than amino acids. The terms alsoencompass an amino acid polymer that has been modified naturally or byintervention; for example disulfide bond formation, glycosylation,lipidation, acetylation, phosphorylation, or any other manipulation ormodification, such as conjugation with a labeling or bioactivecomponent.

As used herein, the terms “antigen” or “immunogen” are usedinterchangeably to refer to a substance, typically a protein, which iscapable of inducing an immune response in a subject. The term alsorefers to proteins that are immunologically active in the sense thatonce administered to a subject (either directly or by administering tothe subject a nucleotide sequence or vector that encodes the protein) isable to evoke an immune response of the humoral and/or cellular typedirected against that protein.

The term “antibody” includes intact molecules as well as fragmentsthereof, such as Fab, F(ab′)₂, Fv and scFv which are capable of bindingthe epitope determinant. These antibody fragments retain some ability toselectively bind with its antigen or receptor and include, for example:

-   -   a. Fab, the fragment which contains a monovalent antigen-binding        fragment of an antibody molecule may be produced by digestion of        whole antibody with the enzyme papain to yield an intact light        chain and a portion of one heavy chain;    -   b. Fab′, the fragment of an antibody molecule may be obtained by        treating whole antibody with pepsin, followed by reduction, to        yield an intact light chain and a portion of the heavy chain;        two Fab′ fragments are obtained per antibody molecule;    -   c. F(ab′)₂, the fragment of the antibody that may be obtained by        treating whole antibody with the enzyme pepsin without        subsequent reduction; F(ab′)2 is a dimer of two Fab′ fragments        held together by two disulfide bonds;    -   d. scFv, including a genetically engineered fragment containing        the variable region of a heavy and a light chain as a fused        single chain molecule.

General methods of making these fragments are known in the art. (See forexample, Harlow and Lane, Antibodies: A Laboratory Manual, Cold SpringHarbor Laboratory, New York (1988), which is incorporated herein byreference).

A “neutralizing antibody” may inhibit the entry of HIV-1 virus forexample SF162 and/or JRCSF with a neutralization index >1.5 or >2.0.Broad and potent neutralizing antibodies may neutralize greater thanabout 50% of HIV-1 viruses (from diverse clades and different strainswithin a clade) in a neutralization assay. The inhibitory concentrationof the monoclonal antibody may be less than about 25 mg/ml to neutralizeabout 50% of the input virus in the neutralization assay.

It should be understood that the proteins, including the antibodiesand/or antigens of the invention may differ from the exact sequencesillustrated and described herein. Thus, the invention contemplatesdeletions, additions and substitutions to the sequences shown, so longas the sequences function in accordance with the methods of theinvention. In this regard, particularly preferred substitutions willgenerally be conservative in nature, i.e., those substitutions that takeplace within a family of amino acids. For example, amino acids aregenerally divided into four families: (1) acidic—aspartate andglutamate; (2) basic—lysine, arginine, histidine; (3) non-polar—alanine,valine, leucine, isoleucine, proline, phenylalanine, methionine,tryptophan; and (4) uncharged polar—glycine, asparagine, glutamine,cysteine, serine threonine, tyrosine. Phenylalanine, tryptophan, andtyrosine are sometimes classified as aromatic amino acids. It isreasonably predictable that an isolated replacement of leucine withisoleucine or valine, or vice versa; an aspartate with a glutamate orvice versa; a threonine with a serine or vice versa; or a similarconservative replacement of an amino acid with a structurally relatedamino acid, will not have a major effect on the biological activity.Proteins having substantially the same amino acid sequence as thesequences illustrated and described but possessing minor amino acidsubstitutions that do not substantially affect the immunogenicity of theprotein are, therefore, within the scope of the invention.

As used herein the terms “nucleotide sequences” and “nucleic acidsequences” refer to deoxyribonucleic acid (DNA) or ribonucleic acid(RNA) sequences, including, without limitation, messenger RNA (mRNA),DNA/RNA hybrids, or synthetic nucleic acids. The nucleic acid may besingle-stranded, or partially or completely double-stranded (duplex).Duplex nucleic acids may be homoduplex or heteroduplex.

As used herein the term “transgene” may used to refer to “recombinant”nucleotide sequences that may be derived from any of the nucleotidesequences encoding the proteins of the present invention. The term“recombinant” means a nucleotide sequence that has been manipulated “byman” and which does not occur in nature, or is linked to anothernucleotide sequence or found in a different arrangement in nature. It isunderstood that manipulated “by man” means manipulated by someartificial means, including by use of machines, codon optimization,restriction enzymes, etc.

For example, in one embodiment the nucleotide sequences may be mutatedsuch that the activity of the encoded proteins in vivo is abrogated. Inanother embodiment the nucleotide sequences may be codon optimized, forexample the codons may be optimized for human use. In preferredembodiments the nucleotide sequences of the invention are both mutatedto abrogate the normal in vivo function of the encoded proteins, andcodon optimized for human use. For example, each of the Gag, Pol, Env,Nef, RT, and Int sequences of the invention may be altered in theseways.

As regards codon optimization, the nucleic acid molecules of theinvention have a nucleotide sequence that encodes the antigens of theinvention and may be designed to employ codons that are used in thegenes of the subject in which the antigen is to be produced. Manyviruses, including HIV and other lentiviruses, use a large number ofrare codons and, by altering these codons to correspond to codonscommonly used in the desired subject, enhanced expression of theantigens may be achieved. In a preferred embodiment, the codons used are“humanized” codons, i.e., the codons are those that appear frequently inhighly expressed human genes (Andre et al., J. Virol. 72:1497-1503,1998) instead of those codons that are frequently used by HIV. Suchcodon usage provides for efficient expression of the transgenic HIVproteins in human cells. Any suitable method of codon optimization maybe used. Such methods, and the selection of such methods, are well knownto those of skill in the art. In addition, there are several companiesthat will optimize codons of sequences, such as Geneart (geneart.com).Thus, the nucleotide sequences of the invention may readily be codonoptimized.

The invention further encompasses nucleotide sequences encodingfunctionally and/or antigenically equivalent variants and derivatives ofthe antigens of the invention and functionally equivalent fragmentsthereof. These functionally equivalent variants, derivatives, andfragments display the ability to retain antigenic activity. Forinstance, changes in a DNA sequence that do not change the encoded aminoacid sequence, as well as those that result in conservativesubstitutions of amino acid residues, one or a few amino acid deletionsor additions, and substitution of amino acid residues by amino acidanalogs are those which will not significantly affect properties of theencoded polypeptide. Conservative amino acid substitutions areglycine/alanine; valine/isoleucine/leucine; asparagine/glutamine;aspartic acid/glutamic acid; serine/threonine/methionine;lysine/arginine; and phenylalanine/tyrosine/tryptophan. In oneembodiment, the variants have at least 50%, at least 55%, at least 60%,at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, atleast 86%, at least 87%, at least 88%, at least 89%, at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98% or at least 99% homology oridentity to the antigen, epitope, immunogen, peptide or polypeptide ofinterest.

For the purposes of the present invention, sequence identity or homologyis determined by comparing the sequences when aligned so as to maximizeoverlap and identity while minimizing sequence gaps. In particular,sequence identity may be determined using any of a number ofmathematical algorithms. A nonlimiting example of a mathematicalalgorithm used for comparison of two sequences is the algorithm ofKarlin & Altschul, Proc. Natl. Acad. Sci. USA 1990; 87: 2264-2268,modified as in Karlin & Altschul, Proc. Natl. Acad. Sci. USA 1993; 90:5873-5877.

Another example of a mathematical algorithm used for comparison ofsequences is the algorithm of Myers & Miller, CABIOS 1988; 4: 11-17.Such an algorithm is incorporated into the ALIGN program (version 2.0)which is part of the GCG sequence alignment software package. Whenutilizing the ALIGN program for comparing amino acid sequences, a PAM120weight residue table, a gap length penalty of 12, and a gap penalty of 4may be used. Yet another useful algorithm for identifying regions oflocal sequence similarity and alignment is the FASTA algorithm asdescribed in Pearson & Lipman, Proc. Natl. Acad. Sci. USA 1988; 85:2444-2448.

Advantageous for use according to the present invention is the WU-BLAST(Washington University BLAST) version 2.0 software. WU-BLAST version 2.0executable programs for several UNIX platforms may be downloaded fromftp://blast.wustl.edu/blast/executables. This program is based onWU-BLAST version 1.4, which in turn is based on the public domainNCBI-BLAST version 1.4 (Altschul & Gish, 1996, Local alignmentstatistics, Doolittle ed., Methods in Enzymology 266: 460-480; Altschulet al., Journal of Molecular Biology 1990; 215: 403-410; Gish & States,1993; Nature Genetics 3: 266-272; Karlin & Altschul, 1993; Proc. Natl.Acad. Sci. USA 90: 5873-5877; all of which are incorporated by referenceherein).

The various recombinant nucleotide sequences and antibodies and/orantigens of the invention are made using standard recombinant DNA andcloning techniques. Such techniques are well known to those of skill inthe art. See for example, “Molecular Cloning: A Laboratory Manual”,second edition (Sambrook et al. 1989).

The nucleotide sequences of the present invention may be inserted into“vectors.” The term “vector” is widely used and understood by those ofskill in the art, and as used herein the term “vector” is usedconsistent with its meaning to those of skill in the art. For example,the term “vector” is commonly used by those skilled in the art to referto a vehicle that allows or facilitates the transfer of nucleic acidmolecules from one environment to another or that allows or facilitatesthe manipulation of a nucleic acid molecule.

Any vector that allows expression of the antibodies and/or antigens ofthe present invention may be used in accordance with the presentinvention. In certain embodiments, the antigens and/or antibodies of thepresent invention may be used in vitro (such as using cell-freeexpression systems) and/or in cultured cells grown in vitro in order toproduce the encoded HIV-antigens and/or antibodies which may then beused for various applications such as in the production of proteinaceousvaccines. For such applications, any vector that allows expression ofthe antigens and/or antibodies in vitro and/or in cultured cells may beused.

For applications where it is desired that the antibodies and/or antigensbe expressed in vivo, for example when the transgenes of the inventionare used in DNA or DNA-containing vaccines, any vector that allows forthe expression of the antibodies and/or antigens of the presentinvention and is safe for use in vivo may be used. In preferredembodiments the vectors used are safe for use in humans, mammals and/orlaboratory animals.

For the antibodies and/or antigens of the present invention to beexpressed, the protein coding sequence should be “operably linked” toregulatory or nucleic acid control sequences that direct transcriptionand translation of the protein. As used herein, a coding sequence and anucleic acid control sequence or promoter are said to be “operablylinked” when they are covalently linked in such a way as to place theexpression or transcription and/or translation of the coding sequenceunder the influence or control of the nucleic acid control sequence. The“nucleic acid control sequence” may be any nucleic acid element, suchas, but not limited to promoters, enhancers, IRES, introns, and otherelements described herein that direct the expression of a nucleic acidsequence or coding sequence that is operably linked thereto. The term“promoter” will be used herein to refer to a group of transcriptionalcontrol modules that are clustered around the initiation site for RNApolymerase II and that when operationally linked to the protein codingsequences of the invention lead to the expression of the encodedprotein. The expression of the transgenes of the present invention maybe under the control of a constitutive promoter or of an induciblepromoter, which initiates transcription only when exposed to someparticular external stimulus, such as, without limitation, antibioticssuch as tetracycline, hormones such as ecdysone, or heavy metals. Thepromoter may also be specific to a particular cell-type, tissue ororgan. Many suitable promoters and enhancers are known in the art, andany such suitable promoter or enhancer may be used for expression of thetransgenes of the invention. For example, suitable promoters and/orenhancers may be selected from the Eukaryotic Promoter Database (EPDB).

The present invention relates to a recombinant vector expressing aforeign epitope. Advantageously, the epitope is an HIV epitope. In anadvantageous embodiment, the HIV epitope is a protein fragment of thepresent invention, however, the present invention may encompassadditional HIV antigens, epitopes or immunogens. Advantageously, the HIVepitope is an HIV antigen, HIV epitope or an HIV immunogen, such as, butnot limited to, the HIV antigens, HIV epitopes or HIV immunogens of U.S.Pat. Nos. 7,341,731; 7,335,364; 7,329,807; 7,323,553; 7,320,859;7,311,920; 7,306,798; 7,285,646; 7,285,289; 7,285,271; 7,282,364;7,273,695; 7,270,997; 7,262,270; 7,244,819; 7,244,575; 7,232,567;7,232,566; 7,223,844; 7,223,739; 7,223,534; 7,223,368; 7,220,554;7,214,530; 7,211,659; 7,211,432; 7,205,159; 7,198,934; 7,195,768;7,192,555; 7,189,826; 7,189,522; 7,186,507; 7,179,645; 7,175,843;7,172,761; 7,169,550; 7,157,083; 7,153,509; 7,147,862; 7,141,550;7,129,219; 7,122,188; 7,118,859; 7,118,855; 7,118,751; 7,118,742;7,105,655; 7,101,552; 7,097,971 7,097,842; 7,094,405; 7,091,049;7,090,648; 7,087,377; 7,083,787; 7,070,787; 7,070,781; 7,060,273;7,056,521; 7,056,519; 7,049,136; 7,048,929; 7,033,593; 7,030,094;7,022,326; 7,009,037; 7,008,622; 7,001,759; 6,997,863; 6,995,008;6,979,535; 6,974,574; 6,972,126; 6,969,609; 6,964,769; 6,964,762;6,958,158; 6,956,059; 6,953,689; 6,951,648; 6,946,075; 6,927,031;6,919,319; 6,919,318; 6,919,077; 6,913,752; 6,911,315; 6,908,617;6,908,612; 6,902,743; 6,900,010; 6,893,869; 6,884,785; 6,884,435;6,875,435; 6,867,005; 6,861,234; 6,855,539; 6,841,381 6,841,345;6,838,477; 6,821,955; 6,818,392; 6,818,222; 6,815,217; 6,815,201;6,812,026; 6,812,025; 6,812,024; 6,808,923; 6,806,055; 6,803,231;6,800,613; 6,800,288; 6,797,811; 6,780,967; 6,780,598; 6,773,920;6,764,682; 6,761,893; 6,753,015; 6,750,005; 6,737,239; 6,737,067;6,730,304; 6,720,310; 6,716,823; 6,713,301; 6,713,070; 6,706,859;6,699,722; 6,699,656; 6,696,291; 6,692,745; 6,670,181; 6,670,115;6,664,406; 6,657,055; 6,657,050; 6,656,471; 6,653,066; 6,649,409;6,649,372; 6,645,732; 6,641,816; 6,635,469; 6,613,530; 6,605,427;6,602,709 6,602,705; 6,600,023; 6,596,477; 6,596,172; 6,593,103;6,593,079; 6,579,673; 6,576,758; 6,573,245; 6,573,040; 6,569,418;6,569,340; 6,562,800; 6,558,961; 6,551,828; 6,551,824; 6,548,275;6,544,780; 6,544,752; 6,544,728; 6,534,482; 6,534,312; 6,534,064;6,531,572; 6,531,313; 6,525,179; 6,525,028; 6,524,582; 6,521,449;6,518,030; 6,518,015; 6,514,691; 6,514,503; 6,511,845; 6,511,812;6,511,801; 6,509,313; 6,506,384; 6,503,882; 6,495,676; 6,495,526;6,495,347; 6,492,123; 6,489,131; 6,489,129; 6,482,614; 6,479,286;6,479,284; 6,465,634; 6,461,615 6,458,560; 6,458,527; 6,458,370;6,451,601; 6,451,592; 6,451,323; 6,436,407; 6,432,633; 6,428,970;6,428,952; 6,428,790; 6,420,139; 6,416,997; 6,410,318; 6,410,028;6,410,014; 6,407,221; 6,406,710; 6,403,092; 6,399,295; 6,392,013;6,391,657; 6,384,198; 6,380,170; 6,376,170; 6,372,426; 6,365,187;6,358,739; 6,355,248; 6,355,247; 6,348,450; 6,342,372; 6,342,228;6,338,952; 6,337,179; 6,335,183; 6,335,017; 6,331,404; 6,329,202;6,329,173; 6,328,976; 6,322,964; 6,319,666; 6,319,665; 6,319,500;6,319,494; 6,316,205; 6,316,003; 6,309,633; 6,306,625 6,296,807;6,294,322; 6,291,239; 6,291,157; 6,287,568; 6,284,456; 6,284,194;6,274,337; 6,270,956; 6,270,769; 6,268,484; 6,265,562; 6,265,149;6,262,029; 6,261,762; 6,261,571; 6,261,569; 6,258,599; 6,258,358;6,248,332; 6,245,331; 6,242,461; 6,241,986; 6,235,526; 6,235,466;6,232,120; 6,228,361; 6,221,579; 6,214,862; 6,214,804; 6,210,963;6,210,873; 6,207,185; 6,203,974; 6,197,755; 6,197,531; 6,197,496;6,194,142; 6,190,871; 6,190,666; 6,168,923; 6,156,302; 6,153,408;6,153,393; 6,153,392; 6,153,378; 6,153,377; 6,146,635; 6,146,614;6,143,876 6,140,059; 6,140,043; 6,139,746; 6,132,992; 6,124,306;6,124,132; 6,121,006; 6,120,990; 6,114,507; 6,114,143; 6,110,466;6,107,020; 6,103,521; 6,100,234; 6,099,848; 6,099,847; 6,096,291;6,093,405; 6,090,392; 6,087,476; 6,083,903; 6,080,846; 6,080,725;6,074,650; 6,074,646; 6,070,126; 6,063,905; 6,063,564; 6,060,256;6,060,064; 6,048,530; 6,045,788; 6,043,347; 6,043,248; 6,042,831;6,037,165; 6,033,672; 6,030,772; 6,030,770; 6,030,618; 6,025,141;6,025,125; 6,020,468; 6,019,979; 6,017,543; 6,017,537; 6,015,694;6,015,661; 6,013,484; 6,013,432 6,007,838; 6,004,811; 6,004,807;6,004,763; 5,998,132; 5,993,819; 5,989,806; 5,985,926; 5,985,641;5,985,545; 5,981,537; 5,981,505; 5,981,170; 5,976,551; 5,972,339;5,965,371; 5,962,428; 5,962,318; 5,961,979; 5,961,970; 5,958,765;5,958,422; 5,955,647; 5,955,342; 5,951,986; 5,951,975; 5,942,237;5,939,277; 5,939,074; 5,935,580; 5,928,930; 5,928,913; 5,928,644;5,928,642; 5,925,513; 5,922,550; 5,922,325; 5,919,458; 5,916,806;5,916,563; 5,914,395; 5,914,109; 5,912,338; 5,912,176; 5,912,170;5,906,936; 5,895,650; 5,891,623; 5,888,726; 5,885,580 5,885,578;5,879,685; 5,876,731; 5,876,716; 5,874,226; 5,872,012; 5,871,747;5,869,058; 5,866,694; 5,866,341; 5,866,320; 5,866,319; 5,866,137;5,861,290; 5,858,740; 5,858,647; 5,858,646; 5,858,369; 5,858,368;5,858,366; 5,856,185; 5,854,400; 5,853,736; 5,853,725; 5,853,724;5,852,186; 5,851,829; 5,851,529; 5,849,475; 5,849,288; 5,843,728;5,843,723; 5,843,640; 5,843,635; 5,840,480; 5,837,510; 5,837,250;5,837,242; 5,834,599; 5,834,441; 5,834,429; 5,834,256; 5,830,876;5,830,641; 5,830,475; 5,830,458; 5,830,457; 5,827,749; 5,827,723;5,824,497 5,824,304; 5,821,047; 5,817,767; 5,817,754; 5,817,637;5,817,470; 5,817,318; 5,814,482; 5,807,707; 5,804,604; 5,804,371;5,800,822; 5,795,955; 5,795,743; 5,795,572; 5,789,388; 5,780,279;5,780,038; 5,776,703; 5,773,260; 5,770,572; 5,766,844; 5,766,842;5,766,625; 5,763,574; 5,763,190; 5,762,965; 5,759,769; 5,756,666;5,753,258; 5,750,373; 5,747,641; 5,747,526; 5,747,028; 5,736,320;5,736,146; 5,733,760; 5,731,189; 5,728,385; 5,721,095; 5,716,826;5,716,637; 5,716,613; 5,714,374; 5,709,879; 5,709,860; 5,709,843;5,705,331; 5,703,057; 5,702,707 5,698,178; 5,688,914; 5,686,078;5,681,831; 5,679,784; 5,674,984; 5,672,472; 5,667,964; 5,667,783;5,665,536; 5,665,355; 5,660,990; 5,658,745; 5,658,569; 5,643,756;5,641,624; 5,639,854; 5,639,598; 5,637,677; 5,637,455; 5,633,234;5,629,153; 5,627,025; 5,622,705; 5,614,413; 5,610,035; 5,607,831;5,606,026; 5,601,819; 5,597,688; 5,593,972; 5,591,829; 5,591,823;5,589,466; 5,587,285; 5,585,254; 5,585,250; 5,580,773; 5,580,739;5,580,563; 5,573,916; 5,571,667; 5,569,468; 5,558,865; 5,556,745;5,550,052; 5,543,328; 5,541,100; 5,541,057; 5,534,406 5,529,765;5,523,232; 5,516,895; 5,514,541; 5,510,264; 5,500,161; 5,480,967;5,480,966; 5,470,701; 5,468,606; 5,462,852; 5,459,127; 5,449,601;5,447,838; 5,447,837; 5,439,809; 5,439,792; 5,418,136; 5,399,501;5,397,695; 5,391,479; 5,384,240; 5,374,519; 5,374,518; 5,374,516;5,364,933; 5,359,046; 5,356,772; 5,354,654; 5,344,755; 5,335,673;5,332,567; 5,320,940; 5,317,009; 5,312,902; 5,304,466; 5,296,347;5,286,852; 5,268,265; 5,264,356; 5,264,342; 5,260,308; 5,256,767;5,256,561; 5,252,556; 5,230,998; 5,230,887; 5,227,159; 5,225,347;5,221,610 5,217,861; 5,208,321; 5,206,136; 5,198,346; 5,185,147;5,178,865; 5,173,400; 5,173,399; 5,166,050; 5,156,951; 5,135,864;5,122,446; 5,120,662; 5,103,836; 5,100,777; 5,100,662; 5,093,230;5,077,284; 5,070,010; 5,068,174; 5,066,782; 5,055,391; 5,043,262;5,039,604; 5,039,522; 5,030,718; 5,030,555; 5,030,449; 5,019,387;5,013,556; 5,008,183; 5,004,697; 4,997,772; 4,983,529; 4,983,387;4,965,069; 4,945,082; 4,921,787; 4,918,166; 4,900,548; 4,888,290;4,886,742; 4,885,235; 4,870,003; 4,869,903; 4,861,707; 4,853,326;4,839,288; 4,833,072 and 4,795,739.

In another embodiment, HIV, or immunogenic fragments thereof, may beutilized as the HIV epitope. For example, the HIV nucleotides of U.S.Pat. Nos. 7,393,949, 7,374,877, 7,306,901, 7,303,754, 7,173,014,7,122,180, 7,078,516, 7,022,814, 6,974,866, 6,958,211, 6,949,337,6,946,254, 6,896,900, 6,887,977, 6,870,045, 6,803,187, 6,794,129,6,773,915, 6,768,004, 6,706,268, 6,696,291, 6,692,955, 6,656,706,6,649,409, 6,627,442, 6,610,476, 6,602,705, 6,582,920, 6,557,296,6,531,587, 6,531,137, 6,500,623, 6,448,078, 6,429,306, 6,420,545,6,410,013, 6,407,077, 6,395,891, 6,355,789, 6,335,158, 6,323,185,6,316,183, 6,303,293, 6,300,056, 6,277,561, 6,270,975, 6,261,564,6,225,045, 6,222,024, 6,194,391, 6,194,142, 6,162,631, 6,114,167,6,114,109, 6,090,392, 6,060,587, 6,057,102, 6,054,565, 6,043,081,6,037,165, 6,034,233, 6,033,902, 6,030,769, 6,020,123, 6,015,661,6,010,895, 6,001,555, 5,985,661, 5,980,900, 5,972,596, 5,939,538,5,912,338, 5,869,339, 5,866,701, 5,866,694, 5,866,320, 5,866,137,5,864,027, 5,861,242, 5,858,785, 5,858,651, 5,849,475, 5,843,638,5,840,480, 5,821,046, 5,801,056, 5,786,177, 5,786,145, 5,773,247,5,770,703, 5,756,674, 5,741,706, 5,705,612, 5,693,752, 5,688,637,5,688,511, 5,684,147, 5,665,577, 5,585,263, 5,578,715, 5,571,712,5,567,603, 5,554,528, 5,545,726, 5,527,895, 5,527,894, 5,223,423,5,204,259, 5,144,019, 5,051,496 and 4,942,122 are useful for the presentinvention.

Any epitope recognized by an HIV antibody may be used in the presentinvention. For example, the anti-HIV antibodies of U.S. Pat. Nos.6,949,337, 6,900,010, 6,821,744, 6,768,004, 6,613,743, 6,534,312,6,511,830, 6,489,131, 6,242,197, 6,114,143, 6,074,646, 6,063,564,6,060,254, 5,919,457, 5,916,806, 5,871,732, 5,824,304, 5,773,247,5,736,320, 5,637,455, 5,587,285, 5,514,541, 5,317,009, 4,983,529,4,886,742, 4,870,003 and 4,795,739 are useful for the present invention.Furthermore, monoclonal anti-HIV antibodies of U.S. Pat. Nos. 7,074,556,7,074,554, 7,070,787, 7,060,273, 7,045,130, 7,033,593, RE39,057,7,008,622, 6,984,721, 6,972,126, 6,949,337, 6,946,465, 6,919,077,6,916,475, 6,911,315, 6,905,680, 6,900,010, 6,825,217, 6,824,975,6,818,392, 6,815,201, 6,812,026, 6,812,024, 6,797,811, 6,768,004,6,703,019, 6,689,118, 6,657,050, 6,608,179, 6,600,023, 6,596,497,6,589,748, 6,569,143, 6,548,275, 6,525,179, 6,524,582, 6,506,384,6,498,006, 6,489,131, 6,465,173, 6,461,612, 6,458,933, 6,432,633,6,410,318, 6,406,701, 6,395,275, 6,391,657, 6,391,635, 6,384,198,6,376,170, 6,372,217, 6,344,545, 6,337,181, 6,329,202, 6,319,665,6,319,500, 6,316,003, 6,312,931, 6,309,880, 6,296,807, 6,291,239,6,261,558, 6,248,514, 6,245,331, 6,242,197, 6,241,986, 6,228,361,6,221,580, 6,190,871, 6,177,253, 6,146,635, 6,146,627, 6,146,614,6,143,876, 6,132,992, 6,124,132, RE36,866, 6,114,143, 6,103,238,6,060,254, 6,039,684, 6,030,772, 6,020,468, 6,013,484, 6,008,044,5,998,132, 5,994,515, 5,993,812, 5,985,545, 5,981,278, 5,958,765,5,939,277, 5,928,930, 5,922,325, 5,919,457, 5,916,806, 5,914,109,5,911,989, 5,906,936, 5,889,158, 5,876,716, 5,874,226, 5,872,012,5,871,732, 5,866,694, 5,854,400, 5,849,583, 5,849,288, 5,840,480,5,840,305, 5,834,599, 5,831,034, 5,827,723, 5,821,047, 5,817,767,5,817,458, 5,804,440, 5,795,572, 5,783,670, 5,776,703, 5,773,225,5,766,944, 5,753,503, 5,750,373, 5,747,641, 5,736,341, 5,731,189,5,707,814, 5,702,707, 5,698,178, 5,695,927, 5,665,536, 5,658,745,5,652,138, 5,645,836, 5,635,345, 5,618,922, 5,610,035, 5,607,847,5,604,092, 5,601,819, 5,597,896, 5,597,688, 5,591,829, 5,558,865,5,514,541, 5,510,264, 5,478,753, 5,374,518, 5,374,516, 5,344,755,5,332,567, 5,300,433, 5,296,347, 5,286,852, 5,264,221, 5,260,308,5,256,561, 5,254,457, 5,230,998, 5,227,159, 5,223,408, 5,217,895,5,180,660, 5,173,399, 5,169,752, 5,166,050, 5,156,951, 5,140,105,5,135,864, 5,120,640, 5,108,904, 5,104,790, 5,049,389, 5,030,718,5,030,555, 5,004,697, 4,983,529, 4,888,290, 4,886,742 and 4,853,326, arealso useful for the present invention.

The present invention relates to a recombinant vector expressing aforeign epitope. Advantageously, the epitope is a SIV epitope. It isunderstood by one of skill in the art that anything referring to HIV inthe specification also applies to SIV. In an advantageous embodiment,the SIV epitope is a protein fragment of the present invention, however,the present invention may encompass additional SIV antigens, epitopes orimmunogens. Advantageously, the SIV epitope is an SIV antigen, SIVepitope or an SIV immunogen, such as, but not limited to, the SIVantigens, SIV epitopes or SIV immunogens of U.S. Pat. Nos. 7,892,729;7,886,962; 7,879,914; 7,829,287; 7,794,998; 7,767,455; 7,759,477;7,758,869; 7,754,420; 7,749,973; 7,748,618; 7,732,124; 7,709,606;7,700,342; 7,700,273; 7,625,917; 7,622,124; 7,611,721; 7,608,422;7,601,518; 7,585,675; 7,534,603; 7,511,117; 7,508,781; 7,507,417;7,479,497; 7,464,352; 7,457,973; 7,442,551; 7,439,052; 7,419,829;7,407,663; 7,378,515; 7,364,760; 7,312,065; 7,261,876; 7,220,554;7,211,240; 7,198,935; 7,169,394; 7,098,201; 7,078,516; 7,070,993;7,048,929; 7,034,010; RE39,057; 7,022,814; 7,018,638; 6,955,919;6,933,377; 6,908,617; 6,902,929; 6,846,477; 6,818,442; 6,803,231;6,800,281; 6,797,811; 6,790,657; 6,712,612; 6,706,729; 6,703,394;6,682,907; 6,656,706; 6,645,956; 6,635,472; 6,596,539; 6,589,763;6,562,571; 6,555,523; 6,555,342; 6,541,009; 6,531,574; 6,531,123;6,503,713; 6,479,281; 6,475,718; 6,469,083; 6,468,539; 6,455,265;6,448,390; 6,440,730; 6,423,544; 6,365,150; 6,362,000; 6,326,007;6,322,969; 6,291,664; 6,277,601; 6,261,571; 6,255,312; 6,207,455;6,194,142; 6,117,656; 6,111,087; 6,107,020; 6,080,846; 6,060,064;6,046,228; 6,043,081; 6,027,731; 6,020,123; 6,017,536; 6,004,781;5,994,515; 5,981,259; 5,961,976; 5,950,176; 5,929,222; 5,928,913;5,912,176; 5,888,726; 5,861,243; 5,861,161; 5,858,366; 5,830,475;5,817,316; 5,804,196; 5,786,177; 5,759,768; 5,747,324; 5,705,522;5,705,331; 5,698,446; 5,688,914; 5,688,637; 5,654,195; 5,650,269;5,631,154; 5,582,967; 5,552,269; 5,512,281; 5,508,166; 5,470,572;5,312,902; 5,310,651; 5,268,265; 5,254,457; 5,212,084; 5,087,631 and4,978,687.

The vectors used in accordance with the present invention shouldtypically be chosen such that they contain a suitable gene regulatoryregion, such as a promoter or enhancer, such that the antigens and/orantibodies of the invention may be expressed.

When the aim is to express the antibodies and/or antigens of theinvention in vivo in a subject, for example in order to generate animmune response against an HIV-1 antigen and/or protective immunityagainst HIV-1, expression vectors that are suitable for expression onthat subject, and that are safe for use in vivo, should be chosen. Forexample, in some embodiments it may be desired to express the antibodiesand/or antigens of the invention in a laboratory animal, such as forpre-clinical testing of the HIV-1 immunogenic compositions and vaccinesof the invention. In other embodiments, it will be desirable to expressthe antibodies and/or antigens of the invention in human subjects, suchas in clinical trials and for actual clinical use of the immunogeniccompositions and vaccine of the invention. Any vectors that are suitablefor such uses may be employed, and it is well within the capabilities ofthe skilled artisan to select a suitable vector. In some embodiments itmay be preferred that the vectors used for these in vivo applicationsare attenuated to vector from amplifying in the subject. For example, ifplasmid vectors are used, preferably they will lack an origin ofreplication that functions in the subject so as to enhance safety for invivo use in the subject. If viral vectors are used, preferably they areattenuated or replication-defective in the subject, again, so as toenhance safety for in vivo use in the subject.

In preferred embodiments of the present invention viral vectors areused. Advantageously, the vector is a CMV vector, preferably lacking oneor more of the glycoproteins US2, US3, US6 and US11. In yet anotherembodiment, all of the genes between US2 and US11 region of the CMVgenome are deleted. In another embodiment, where superinfectivity orrepeated infectivity is desired, any vector, advantageously a viralvector, may express one or more of the glycoproteins US2, US3, US6 andUS11. Viral expression vectors are well known to those skilled in theart and include, for example, viruses such as adenoviruses,adeno-associated viruses (AAV), alphaviruses, herpesviruses,retroviruses and poxviruses, including avipox viruses, attenuatedpoxviruses, vaccinia viruses, and particularly, the modified vacciniaAnkara virus (MVA; ATCC Accession No. VR-1566). Such viruses, when usedas expression vectors are innately non-pathogenic in the selectedsubjects such as humans or have been modified to render themnon-pathogenic in the selected subjects. For example,replication-defective adenoviruses and alphaviruses are well known andmay be used as gene delivery vectors. However, these vectors areimmunogenic and induce immunity against the vector which prohibits theirrepeated use unless they express US2-11.

In an embodiment where superinfectivity or repeated infectivity isdesired, any vector, advantageously a viral vector, may express one ormore of the glycoproteins US2, US3, US6 and US11. In a particularlyadvantageous embodiment, the vector expresses glycoproteins US2, US3,US6 and US11. More advantageously, the vector contains and expresses allof the glycoproteins within the US2 to US11 region of CMV. In anadvantageous embodiment, the one or more of the glycoproteins US2, US3,US6 and US11 may include, but not limited to, the glycoproteins of U.S.Pat. Nos. 7,892,564; 7,749,745; 7,364,893; 6,953,661; 6,913,751;6,740,324; 6,613,892; 6,410,033; 6,140,114; 6,103,531; 6,033,671;5,908,780; 5,906,935; 5,874,279; 5,853,733; 5,846,806; 5,843,458;5,837,532; 5,804,372; 5,753,476; 5,741,696; 5,731,188; 5,720,957;5,676,952; 5,599,544; 5,593,873 and 5,334,498.

The nucleotide sequences and vectors of the invention may be deliveredto cells, for example if aim is to express and the HIV-1 antigens incells in order to produce and isolate the expressed proteins, such asfrom cells grown in culture. For expressing the antibodies and/orantigens in cells any suitable transfection, transformation, or genedelivery methods may be used. Such methods are well known by thoseskilled in the art, and one of skill in the art would readily be able toselect a suitable method depending on the nature of the nucleotidesequences, vectors, and cell types used. For example, transfection,transformation, microinjection, infection, electroporation, lipofection,or liposome-mediated delivery could be used. Expression of theantibodies and/or antigens may be carried out in any suitable type ofhost cells, such as bacterial cells, yeast, insect cells, and mammaliancells. The antibodies and/or antigens of the invention may also beexpressed using including in vitro transcription/translation systems.All of such methods are well known by those skilled in the art, and oneof skill in the art would readily be able to select a suitable methoddepending on the nature of the nucleotide sequences, vectors, and celltypes used.

In preferred embodiments, the nucleotide sequences, antibodies and/orantigens of the invention are administered in vivo, for example wherethe aim is to produce an immunogenic response in a subject. A “subject”in the context of the present invention may be any animal. For example,in some embodiments it may be desired to express the transgenes of theinvention in a laboratory animal, such as for pre-clinical testing ofthe HIV-1 immunogenic compositions and vaccines of the invention. Inother embodiments, it will be desirable to express the antibodies and/orantigens of the invention in human subjects, such as in clinical trialsand for actual clinical use of the immunogenic compositions and vaccineof the invention. In preferred embodiments the subject is a human, forexample a human that is infected with, or is at risk of infection with,HIV-1.

For such in vivo applications the nucleotide sequences, antibodiesand/or antigens of the invention are preferably administered as acomponent of an immunogenic composition which may comprise thenucleotide sequences and/or antigens of the invention in admixture witha pharmaceutically acceptable carrier. The immunogenic compositions ofthe invention are useful to stimulate an immune response against HIV-1and may be used as one or more components of a prophylactic ortherapeutic vaccine against HIV-1 for the prevention, amelioration ortreatment of AIDS. The nucleic acids and vectors of the invention areparticularly useful for providing genetic vaccines, i.e. vaccines fordelivering the nucleic acids encoding the antibodies and/or antigens ofthe invention to a subject, such as a human, such that the antibodiesand/or antigens are then expressed in the subject to elicit an immuneresponse.

The compositions of the invention may be injectable suspensions,solutions, sprays, lyophilized powders, syrups, elixirs and the like.Any suitable form of composition may be used. To prepare such acomposition, a nucleic acid or vector of the invention, having thedesired degree of purity, is mixed with one or more pharmaceuticallyacceptable carriers and/or excipients. The carriers and excipients mustbe “acceptable” in the sense of being compatible with the otheringredients of the composition. Acceptable carriers, excipients, orstabilizers are nontoxic to recipients at the dosages and concentrationsemployed, and include, but are not limited to, water, saline, phosphatebuffered saline, dextrose, glycerol, ethanol, or combinations thereof,buffers such as phosphate, citrate, and other organic acids;antioxidants including ascorbic acid and methionine; preservatives (suchas octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride;benzalkonium chloride, benzethonium chloride; phenol, butyl or benzylalcohol; alkyl parabens such as methyl or propyl paraben; catechol;resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecularweight (less than about 10 residues) polypeptide; proteins, such asserum albumin, gelatin, or immunoglobulins; hydrophilic polymers such aspolyvinylpyrrolidone; amino acids such as glycine, glutamine,asparagine, histidine, arginine, or lysine; monosaccharides,disaccharides, and other carbohydrates including glucose, mannose, ordextrins; chelating agents such as EDTA; sugars such as sucrose,mannitol, trehalose or sorbitol; salt-forming counter-ions such assodium; metal complexes (e.g., Zn-protein complexes); and/or non-ionicsurfactants such as TWEEN™, PLURONICS™ or polyethylene glycol (PEG).

An immunogenic or immunological composition may also be formulated inthe form of an oil-in-water emulsion. The oil-in-water emulsion may bebased, for example, on light liquid paraffin oil (European Pharmacopeatype); isoprenoid oil such as squalane, squalene, EICOSANE™ ortetratetracontane; oil resulting from the oligomerization of alkene(s),e.g., isobutene or decene; esters of acids or of alcohols containing alinear alkyl group, such as plant oils, ethyl oleate, propylene glycoldi(caprylate/caprate), glyceryl tri(caprylate/caprate) or propyleneglycol dioleate; esters of branched fatty acids or alcohols, e.g.,isostearic acid esters. The oil advantageously is used in combinationwith emulsifiers to form the emulsion. The emulsifiers may be nonionicsurfactants, such as esters of sorbitan, mannide (e.g., anhydromannitololeate), glycerol, polyglycerol, propylene glycol, and oleic,isostearic, ricinoleic, or hydroxystearic acid, which are optionallyethoxylated, and polyoxypropylene-polyoxyethylene copolymer blocks, suchas the Pluronic® products, e.g., L121. The adjuvant may be a mixture ofemulsifier(s), micelle-forming agent, and oil such as that which iscommercially available under the name Provax® (IDEC Pharmaceuticals, SanDiego, Calif.).

The immunogenic compositions of the invention may contain additionalsubstances, such as wetting or emulsifying agents, buffering agents, oradjuvants to enhance the effectiveness of the vaccines (Remington'sPharmaceutical Sciences, 18th edition, Mack Publishing Company, (ed.)1980).

Adjuvants may also be included. Adjuvants include, but are not limitedto, mineral salts (e.g., AlK(SO₄)₂, AlNa(SO₄)₂, AlNH(SO₄)₂, silica,alum, Al(OH)₃, Ca₃(PO₄)₂, kaolin, or carbon), polynucleotides with orwithout immune stimulating complexes (ISCOMs) (e.g., CpGoligonucleotides, such as those described in Chuang, T. H. et al, (2002)J. Leuk. Biol. 71(3): 538-44; Ahmad-Nejad, P. et al (2002) Eur. J.Immunol. 32(7): 1958-68; poly IC or poly AU acids, polyarginine with orwithout CpG (also known in the art as IC31; see Schellack, C. et al(2003) Proceedings of the 34^(th) Annual Meeting of the German Societyof Immunology; Lingnau, K. et al (2002) Vaccine 20(29-30): 3498-508),JuvaVax™ (U.S. Pat. No. 6,693,086), certain natural substances (e.g.,wax D from Mycobacterium tuberculosis, substances found inCornyebacterium parvum, Bordetella pertussis, or members of the genusBrucella), flagellin (Toll-like receptor 5 ligand; see McSorley, S. J.et al (2002) J. Immunol. 169(7): 3914-9), saponins such as QS21, QS17,and QS7 (U.S. Pat. Nos. 5,057,540; 5,650,398; 6,524,584; 6,645,495),monophosphoryl lipid A, in particular, 3-de-O-acylated monophosphoryllipid A (3D-MPL), imiquimod (also known in the art as IQM andcommercially available as Aldara®; U.S. Pat. Nos. 4,689,338; 5,238,944;Zuber, A. K. et al (2004) 22(13-14): 1791-8), and the CCR5 inhibitorCMPD167 (see Veazey, R. S. et al (2003) J. Exp. Med. 198: 1551-1562).

Aluminum hydroxide or phosphate (alum) are commonly used at 0.05 to 0.1%solution in phosphate buffered saline. Other adjuvants that may be used,especially with DNA vaccines, are cholera toxin, especiallyCTA1-DD/ISCOMs (see Mowat, A. M. et al (2001) J. Immunol. 167(6):3398-405), polyphosphazenes (Allcock, H. R. (1998) App. OrganometallicChem. 12(10-11): 659-666; Payne, L. G. et al (1995) Pharm. Biotechnol.6: 473-93), cytokines such as, but not limited to, IL-2, IL-4, GM-CSF,IL-12, IL-15 IGF-1, IFN-α, IFN-β, and IFN-γ (Boyer et al., (2002) J.Liposome Res. 121:137-142; WO01/095919), immunoregulatory proteins suchas CD40L (ADX40; see, for example, WO03/063899), and the CD1a ligand ofnatural killer cells (also known as CRONY or α-galactosyl ceramide; seeGreen, T. D. et al, (2003) J. Virol. 77(3): 2046-2055),immunostimulatory fusion proteins such as IL-2 fused to the Fc fragmentof immunoglobulins (Barouch et al., Science 290:486-492, 2000) andco-stimulatory molecules B7.1 and B7.2 (Boyer), all of which may beadministered either as proteins or in the form of DNA, on the sameexpression vectors as those encoding the antigens of the invention or onseparate expression vectors.

The immunogenic compositions may be designed to introduce the nucleicacids or expression vectors to a desired site of action and release itat an appropriate and controllable rate. Methods of preparingcontrolled-release formulations are known in the art. For example,controlled release preparations may be produced by the use of polymersto complex or absorb the immunogen and/or immunogenic composition. Acontrolled-release formulations may be prepared using appropriatemacromolecules (for example, polyesters, polyamino acids, polyvinyl,pyrrolidone, ethylenevinylacetate, methylcellulose,carboxymethylcellulose, or protamine sulfate) known to provide thedesired controlled release characteristics or release profile. Anotherpossible method to control the duration of action by acontrolled-release preparation is to incorporate the active ingredientsinto particles of a polymeric material such as, for example, polyesters,polyamino acids, hydrogels, polylactic acid, polyglycolic acid,copolymers of these acids, or ethylene vinylacetate copolymers.Alternatively, instead of incorporating these active ingredients intopolymeric particles, it is possible to entrap these materials intomicrocapsules prepared, for example, by coacervation techniques or byinterfacial polymerization, for example, hydroxymethylcellulose orgelatin-microcapsule and poly-(methylmethacrylate) microcapsule,respectively, in colloidal drug delivery systems (for example,liposomes, albumin microspheres, microemulsions, nano-particles andnanocapsules) or in macroemulsions. Such techniques are disclosed in NewTrends and Developments in Vaccines, Voller et al. (eds.), UniversityPark Press, Baltimore, Md., 1978 and Remington's PharmaceuticalSciences, 16th edition.

Suitable dosages of the nucleic acids and expression vectors of theinvention (collectively, the immunogens) in the immunogenic compositionof the invention may be readily determined by those of skill in the art.For example, the dosage of the immunogens may vary depending on theroute of administration and the size of the subject. Suitable doses maybe determined by those of skill in the art, for example by measuring theimmune response of a subject, such as a laboratory animal, usingconventional immunological techniques, and adjusting the dosages asappropriate. Such techniques for measuring the immune response of thesubject include but are not limited to, chromium release assays,tetramer binding assays, IFN-γ ELISPOT assays, IL-2 ELISPOT assays,intracellular cytokine assays, and other immunological detection assays,e.g., as detailed in the text “Antibodies: A Laboratory Manual” by EdHarlow and David Lane.

When provided prophylactically, the immunogenic compositions of theinvention are ideally administered to a subject in advance of HIVinfection, or evidence of HIV infection, or in advance of any symptomdue to AIDS, especially in high-risk subjects. The prophylacticadministration of the immunogenic compositions may serve to provideprotective immunity of a subject against HIV-1 infection or to preventor attenuate the progression of AIDS in a subject already infected withHIV-1. When provided therapeutically, the immunogenic compositions mayserve to ameliorate and treat AIDS symptoms and are advantageously usedas soon after infection as possible, preferably before appearance of anysymptoms of AIDS but may also be used at (or after) the onset of thedisease symptoms.

The immunogenic compositions may be administered using any suitabledelivery method including, but not limited to, intramuscular,intravenous, intradermal, mucosal, and topical delivery. Such techniquesare well known to those of skill in the art. More specific examples ofdelivery methods are intramuscular injection, intradermal injection, andsubcutaneous injection. However, delivery need not be limited toinjection methods. Further, delivery of DNA to animal tissue has beenachieved by cationic liposomes (Watanabe et al., (1994) Mol. Reprod.Dev. 38:268-274; and WO 96/20013), direct injection of naked DNA intoanimal muscle tissue (Robinson et al., (1993) Vaccine 11:957-960;Hoffman et al., (1994) Vaccine 12: 1529-1533; Xiang et al., (1994)Virology 199: 132-140; Webster et al., (1994) Vaccine 12: 1495-1498;Davis et al., (1994) Vaccine 12: 1503-1509; and Davis et al., (1993)Hum. Mol. Gen. 2: 1847-1851), or intradermal injection of DNA using“gene gun” technology (Johnston et al., (1994) Meth. Cell Biol.43:353-365). Alternatively, delivery routes may be oral, intranasal orby any other suitable route. Delivery also be accomplished via a mucosalsurface such as the anal, vaginal or oral mucosa.

Immunization schedules (or regimens) are well known for animals(including humans) and may be readily determined for the particularsubject and immunogenic composition. Hence, the immunogens may beadministered one or more times to the subject. Preferably, there is aset time interval between separate administrations of the immunogeniccomposition. While this interval varies for every subject, typically itranges from 10 days to several weeks, and is often 2, 4, 6 or 8 weeks.For humans, the interval is typically from 2 to 6 weeks. In aparticularly advantageous embodiment of the present invention, theinterval is longer, advantageously about 10 weeks, 12 weeks, 14 weeks,16 weeks, 18 weeks, 20 weeks, 22 weeks, 24 weeks, 26 weeks, 28 weeks, 30weeks, 32 weeks, 34 weeks, 36 weeks, 38 weeks, 40 weeks, 42 weeks, 44weeks, 46 weeks, 48 weeks, 50 weeks, 52 weeks, 54 weeks, 56 weeks, 58weeks, 60 weeks, 62 weeks, 64 weeks, 66 weeks, 68 weeks or 70 weeks. Ina most advantageous embodiment, the interval is about 16 weeks or about53 weeks.

The immunization regimes typically have from 1 to 6 administrations ofthe immunogenic composition, but may have as few as one or two or four.The methods of inducing an immune response may also includeadministration of an adjuvant with the immunogens. In some instances,annual, biannual or other long interval (5-10 years) boosterimmunization may supplement the initial immunization protocol.

The present methods also include a variety of prime-boost regimens, forexample DNA prime-Adenovirus boost regimens. In these methods, one ormore priming immunizations are followed by one or more boostingimmunizations. The actual immunogenic composition may be the same ordifferent for each immunization and the type of immunogenic composition(e.g., containing protein or expression vector), the route, andformulation of the immunogens may also be varied. For example, if anexpression vector is used for the priming and boosting steps, it mayeither be of the same or different type (e.g., DNA or bacterial or viralexpression vector). One useful prime-boost regimen provides for twopriming immunizations, four weeks apart, followed by two boostingimmunizations at 4 and 8 weeks after the last priming immunization. Itshould also be readily apparent to one of skill in the art that thereare several permutations and combinations that are encompassed using theDNA, bacterial and viral expression vectors of the invention to providepriming and boosting regimens. In the event that the viral vectorsexpress US2-11 they may be used repeatedly while expressing differentantigens derived from different pathogens.

A specific embodiment of the invention provides methods of inducing animmune response against HIV in a subject by administering an immunogeniccomposition of the invention, preferably which may comprise an US2-11expressing adenovirus vector containing DNA encoding one or more of theepitopes of the invention, one or more times to a subject wherein theepitopes are expressed at a level sufficient to induce a specific immuneresponse in the subject. Such immunizations may be repeated multipletimes at time intervals of at least 2, 4 or 6 weeks (or more) inaccordance with a desired immunization regime.

The immunogenic compositions of the invention may be administered alone,or may be co-administered, or sequentially administered, with other HIVimmunogens and/or HIV immunogenic compositions, e.g., with “other”immunological, antigenic or vaccine or therapeutic compositions therebyproviding multivalent or “cocktail” or combination compositions of theinvention and methods of employing them. Again, the ingredients andmanner (sequential or co-administration) of administration, as well asdosages may be determined taking into consideration such factors as theage, sex, weight, species and condition of the particular subject, andthe route of administration.

When used in combination, the other HIV immunogens may be administeredat the same time or at different times as part of an overallimmunization regime, e.g., as part of a prime-boost regimen or otherimmunization protocol. In an advantageous embodiment, the other HIVimmunogen is env, preferably the HIV env trimer.

Many other HIV immunogens are known in the art, one such preferredimmunogen is HIVA (described in WO 01/47955), which may be administeredas a protein, on a plasmid (e.g., pTHr.HIVA) or in a viral vector (e.g.,MVA.HIVA). Another such HIV immunogen is RENTA (described inPCT/US2004/037699), which may also be administered as a protein, on aplasmid (e.g., pTHr.RENTA) or in a viral vector (e.g., MVA.RENTA).

For example, one method of inducing an immune response against HIV in ahuman subject may comprise administering at least one priming dose of anHIV immunogen and at least one boosting dose of an HIV immunogen,wherein the immunogen in each dose may be the same or different,provided that at least one of the immunogens is an epitope of thepresent invention, a nucleic acid encoding an epitope of the inventionor an expression vector, preferably a VSV vector, encoding an epitope ofthe invention, and wherein the immunogens are administered in an amountor expressed at a level sufficient to induce an HIV-specific immuneresponse in the subject. The HIV-specific immune response may include anHIV-specific T-cell immune response or an HIV-specific B-cell immuneresponse. Such immunizations may be done at intervals, preferably of atleast 2-6 or more weeks.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations may be made herein without departing from the spirit andscope of the invention as defined in the appended claims.

EXAMPLES Example 1 Evasion of CD8⁺ T Cells is Critical forSuperinfection by Cytomegalovirus

Cytomegalovirus (CMV) may superinfect persistently infected hostsdespite CMV-specific humoral and cellular immunity; however, how it doesso remains undefined. Applicants have demonstrated that superinfectionof rhesus CMV-infected rhesus macaques (RM) requires evasion of CD8⁺ Tcell immunity by virally encoded inhibitors of major histocompatibilitycomplex class I (MHC-I) antigen presentation, particularly the homologsof human CMV US2, 3, 6, and 11. In contrast, MHC-I interference wasdispensable for primary infection of RM, or for the establishment of apersistent secondary infection in CMV-infected RM transiently depletedof CD8⁺ lymphocytes. These findings demonstrate that US2-11glycoproteins promote evasion of CD8⁺ T cells in vivo, thus supportingviral replication and dissemination during superinfection, a processthat complicates the development of preventive CMV vaccines but that maybe exploited for CMV-based vector development.

A general characteristic of the adaptive immune response to viruses isits ability to prevent or rapidly extinguish secondary infections byidentical or closely related viruses. A notable exception is theherpesvirus family member cytomegalovirus (CMV), which may repeatedlyestablish persistent infection in immunocompetent hosts (S. B. Boppanaet al. N. Engl. J. Med. 344, 1366 (2001), S. Gorman et al., J. Gen.Virol. 87, 1123 (2006) and S. G. Hansen et al., Nat. Med. 15, 293(2009)). Sequential infections are likely the reason for the presence ofmultiple human CMV (HCMV) genotypes in the human host (Meyer-König etal. Lancet 352, 1280 (1998)). This ability to establish secondarypersistent infections despite the preexistence of persistent virus(referred to as “superinfection”) is particularly notable becausehealthy CMV-infected individuals develop high-titer neutralizingantibody responses and manifest very-high-frequency CD4⁺ and CD8⁺CMV-specific T cell responses (>10% of circulating memory T cells may beCMV-specific) (A. W. Sylwester et al., J. Exp. Med. 202, 673 (2005)).This evasion of pre-existing immunity has frustrated attempts to developpreventive CMV vaccines (S. P. Adler et al., J. Infect. Dis. 171, 26(1995) and S. A. Plotkin et al., J. Infect. Dis. 159, 860 (1989)) butmay be exploited for the development of CMV vectors capable ofrepeatedly initiating de novo T cell responses to heterologous pathogensin CMV-positive hosts (S. G. Hansen et al., Nat. Med. 15, 293 (2009)).

The biologic importance of this superinfection capability has promptedApplicants' investigation of its extent and mechanism. Applicantspreviously showed that inoculation of RhCMV⁺ rhesus macaques (RM) with10⁷ plaque-forming units (PFU) of genetically modified RhCMV (strain68-1) expressing simian immunodeficiency virus (SIV) antigens resultedin superinfection manifested by the persistent shedding of thegenetically modified CMV in the urine and saliva and by the inductionand long-term maintenance of de novo CD4⁺ and CD8⁺ T cell responsesspecific for the SIV insert (S. G. Hansen et al., Nat. Med. 15, 293(2009)). To determine whether RhCMV would be able to overcome immunityat lower, more physiologic doses of infection, as reported for HCMV (S.A. Plotkin et al. J. Infect. Dis. 159, 860 (1989)), a recombinant RhCMVcontaining a loxP-flanked expression cassette for SIVgag [RhCMV(gagL)](FIG. 5) was inoculated subcutaneously at doses of 10⁴ or 10² PFU intofour RM naturally infected by RhCMV, as manifested by the presence ofrobust RhCMV-specific T cell responses (Table 1A). The SIVgag-specific Tcell responses in peripheral blood mononuclear cells (PBMC) or inbroncho-alveolar lavage lymphocytes (BAL) were monitored by flowcytometric analysis of intracellular cytokine staining (ICCS) (FIGS. 6and 7) after stimulation with consecutive overlapping 15-amino acidpeptides corresponding to SIVgag. Reduction of the inoculating dose hadminimal impact on superinfection dynamics: All animals developedSIVgag-specific T cell responses within 2 weeks (FIG. 1A), and secretionof SIVgag-expressing virus in urine or buccal swabs was observed within4 to 10 weeks of infection in both cohorts (FIG. 1B). The time to firstdetection of secreted virus in these low-dose-challenged RM was notmaterially different from that of eight RhCMV⁺ animals infected with 10⁷PFU of RhCMV(gagL) (FIG. 1B). Moreover, the SIVgag-specific T cellresponses and RhCMV(gagL) secretion were stable for more than 3 yearsregardless of initial dose (FIGS. 1, A and C). These data indicate that,consistent with HCMV in humans, RhCMV is able to overcome high levels ofCMV-specific immunity and to establish secondary persistent infections,even with low doses of challenge virus.

TABLE 1 Baseline RhCMV-specific T cell responses in PBMC of study RM.Shown are the animal numbers as well as the percent RhCMV-specific CD4+and CD8+ T cells measured by intracellular cytokine staining. FiguresInfecting Virus RM# CD4 CD8 A FIG. 1 10⁴PFU 21985 1.70 0.68 RhCMV (gagL)22046 1.29 0.37 22463 1.27 0.36 22499 1.71 0.30 10²PFU 22052 2.04 0.12RhCMV (gagL) 22063 2.37 0.43 22511 3.16 0.55 22559 1.05 0.42 avg ± sd1.82 ± 0.69 0.41 ± 0.16 B FIG. 2 ΔUS2-11 (gag) 21973 0 0 24350 0 0ΔVIHCEΔUS2-11 23609 0 0 (gag) 23634 0 0 avg ± sd 0 0 C FIG. 3 ΔVIHCE(gag) 23101 2.112 0.576 ΔRh186-8 23126 2.242 0.809 (retanef) 23132 2.2731.343 23244 3.295 0.779 avg ± sd 2.48 ± 0.55 0.88 ± 0.33 D FIG. 4ΔVIHCEΔUS2-11 21308 0.612 0.197 (gag) 21456 1.167 0.238 ΔUS2-11 (gag)21794 0.961 0.214 23923 0.942 0.166 avg ± sd 0.92 ± 0.23 0.21 ± 0.03

Applicants hypothesized that an essential step during CMV superinfectionis the ability of the virus to clear an initial immunologicalcheckpoint. A likely candidate for such an immunological barrier is CD8⁺cytotoxic T cells (CTL), because they are crucial for controllingCMV-associated diseases (E. A. Walter et al., N. Engl. J. Med. 333, 1038(1995)). The importance of CTL control for CMV is also suggested byviral expression of multiple proteins that inhibit presentation of viralpeptide antigens to CD8⁺ T cells via major histocompatibility complexclass I (MHC-I) molecules (A. K. Pinto, A. B. Hill, Viral Immunol. 18,434 (2005)). HCMV encodes at least four related glycoproteins, each witha unique mechanism to prevent antigen presentation: US2 and US11 mediatethe retrograde translocation of MHC-I into the cytosol for proteasomaldestruction (F. J. van der Wal et al. Curr. Top. Microbiol. Immunol.269, 37 (2002)), US3 retains MHC-I in the endoplasmic reticulum byinterfering with chaperone-controlled peptide loading (Z. Liu et al.Int. J. Biochem. Cell Biol. 41, 503 (2009)), and US6 inhibits thetranslocation of viral and host peptides across the endoplasmicreticulum membrane by the dedicated peptide transporter TAP (transporterassociated with antigen processing) (E. W. Hewitt et al. EMBO J. 20, 387(2001)). RhCMV encodes sequence and functional homologs of these genesin a genomic region spanning Rh182 (US2) to Rh189 (US11) (FIG. 5) (N. T.Pande et al. J. Virol. 79, 5786 (2005)). Furthermore, the Rh178 geneencodes the RhCMV-specific viral inhibitor of heavy chain expression(VIHCE), which prevents signal-sequence-dependenttranslation/translocation of MHC-I (C. J. Powers, K. Früh, PLoS Pathog.4, e1000150 (2008)).

To determine whether MHC-I interference and CTL evasion played a role inthe ability of CMV to superinfect CMV⁺ animals, Applicants replaced theentire RhUS2-11 region with a SIVgag expression cassette using bacterialartificial chromosome (BAC) mutagenesis, resulting in virusΔUS2-11(gag). Applicants also deleted Rh178 to generateΔVIHCEΔUS2-11(gag) (FIG. 5). Applicants previously showed that MHC-Iexpression is partially restored upon US2-11 deletion, whereasadditional deletion of Rh178 fully restores MHC-I expression inRhCMV-infected fibroblasts (C. J. Powers, K. Früh, PLoS Pathog. 4,e1000150 (2008)). In vitro analysis showed that all viruses were deletedfor the targeted RhCMV open reading frames (ORFs), did not contain anyunwanted mutations, and replicated comparably to wild-type RhCMV (FIGS.8 and 9). First, Applicants examined whether these viruses were able toinfect animals that were CMV-naïve as shown by a lack of CMV-specific Tcell responses (Table 1B). Three groups of animals were challenged with10⁷ PFU of ΔUS2-11(gag) (n=2), ΔVIHCEΔUS2-11(gag) (n=2), or BAC-derived(wild-type) RhCMV(gag) (n=2). T cell responses against both CMV andSIVgag in PBMC and against SIVgag in BAL were comparable between animalsinfected with the deletion mutants and the wild-type RhCMV(gag) control(FIG. 2A). Moreover, all animals secreted SIVgag-expressing virus fromday 56 onward for the duration of the experiment (>700 days) (FIG. 2B).Polymerase chain reaction (PCR) analysis of DNA isolated from urinecocultured virus at day 428 confirmed that the secreted viruses lackedthe respective gene regions and were able to persist in the host (FIG.2C). Together these results show that viral MHC-I interference isdispensable for primary infection and the establishment and maintenanceof persistent infection, despite the development of a substantialCMV-specific T cell response.

To examine whether viral MHC-I interference was required forsuperinfection of RhCMV⁺ RM, Applicants challenged two cohorts of fournaturally infected RM each with 10⁷ PFU of ΔVIHCEΔUS2-11(gag) orRhCMV(gag). All animals displayed immediate early gene (IE)-specificCD4⁺ and CD8⁺ T cell responses before challenge (FIG. 3A and Table 1C).In keeping with previous results (S. G. Hansen et al., Nat. Med. 15, 293(2009)), RM inoculated with wild-type RhCMV(gag) displayed boosting ofthe RhCMV-specific T cell response and developed a SIVgag-specificimmune response (FIGS. 3, A and B, insets). They also secretedSIVgag-expressing virus (FIG. 3C). In contrast, Applicants did notdetect SIVgag-specific T cell responses in PBMC or BAL in RM inoculatedwith ΔVIHCEΔUS2-11(gag), even after repeated inoculation (FIGS. 3, A andB), and SIVgag-expressing virus was not detected in secretions (FIG.3C). These results suggested that MHC-I interference was essential forsuperinfection. Inoculation of the same animals with ΔUS2-11(gag) and,later, ΔVIHCE(gag) demonstrated that superinfection required theconserved US2-11 region but not the VIHCE region. The development ofSIVgag-specific CD4⁺ and CD8⁺ T cell responses in blood and BAL (FIGS.3, A and B), as well as the boosting of preexisting RhCMV-specific CD4⁺and CD8⁺ T cell responses in blood (FIG. 3A), or shedding ofSIVgag-expressing RhCMV (FIG. 3D) were only detectable after challengewith ΔVIHCE(gag) but not with ΔUS2-11(gag).

Applicants' results show that genes within the US2-11 region areessential for superinfection, which is consistent with the knownfunction of US2, US3, US6, and US11 as inhibitors of MHC-I antigenpresentation. There are, however, three genes of unknown function (Rh186to Rh188) encoded between US6 and US11. Rh186 and Rh187 are most closelyrelated to the HCMV glycoproteins US8 and US10, respectively (N. T.Pande et al. J. Virol. 79, 5786 (2005)), whereas Rh188 is anuncharacterized RhCMV-specific ORF. Although binding of HCMV-US8 andUS10 to MHC-I has been reported, it is unclear whether this affectsantigen presentation because MHC-I surface expression is not reduced byUS8 or US10 from either HCMV or RhCMV (N. T. Pande et al. J. Virol. 79,5786 (2005), R. S. Tirabassi, H. L. Ploegh, J. Virol. 76, 6832 (2002)and M. H. Furman et al., J. Virol. 76, 11753 (2002)). To determinewhether Rh186, Rh187, or Rh188 are required for superinfection,Applicants generated deletion virus ΔRh186-8. To enable us to monitorsuperinfection by this recombinant in the same cohort of animals thathad already been reinfected with ΔVIHCE(gag), Applicants applied adistinct immunological marker, SlVretanef, a fusion-protein consistingof SIV proteins rev, tat, and nef (S. G. Hansen et al., Nat. Med. 15,293 (2009)). ΔRh186-8(retanef) is deleted for Rh186-188 and contains theRetanef expression cassette between the ORFs Rh213 and Rh214 (FIG. 5).Applicants inoculated the same cohort with ΔRh186-8(retanef) andmonitored the T cell response to this fusion protein as well as toRhCMV-IE and SIVgag using corresponding peptides. As shown in FIGS. 3, Aand B, all four RM developed a SlVretanef-specific T cell responsewithin 2 weeks post-challenge, indicating successful superinfection.Moreover, virus expressing SlVretanef was shed in the secretions ofinfected animals together with SIVgag-expressing ΔVIHCE(gag) (FIG. 3D).Applicants thus conclude that the Rh186-8 region is dispensable forsuperinfection.

Together, Applicants' results suggested that RhCMV was unable tosuperinfect in the absence of the homologs of US2, US3, US6, and US11because the virus was no longer able to avoid elimination by CTL. Tofurther examine this hypothesis, a new group of RhCMV⁺ RM (Table 1D) wasdepleted for CD8⁺ lymphocytes by treatment with cM-T807, a humanizedmonoclonal antibody to CD8, before superinfection with ΔUS2-11(gag) orΔVIHCEΔUS2-11(gag). Flow cytometric analysis of total CD8⁺ T cellsrevealed that depletion was extensive, but transient, with detectableCD8⁺ T cell recovery beginning on day 21 after challenge (FIGS. 4, A andB). Upon inoculation with ΔUS2-11(gag) or ΔVIHCEΔUS2-11(gag),SIVgag-specific CD4⁺ T cell responses were recorded as early as day 7post-challenge, showing the ability of the deletion viruses tosuperinfect these animals (FIG. 4C). Moreover, SIVgag-specific CD8⁺ Tcells were observed within the rebounding CD8⁺ T cells in blood and BALat day 21 in two RM and at day 28 in a third; in the fourth RM, suchresponses were only observed in BAL after day 56. From these data,Applicants conclude that CD8⁺ lymphocytes, most likely CD8⁺ T cells,were essential for preventing superinfection by ΔUS2-11 virus, stronglyindicating that the MHC-I inhibitory function of these molecules isnecessary for superinfection of the CMV-positive host. Notably,CMV-specific CD8⁺ T cells were unable to eliminate RhCMV lacking MHC-Iinhibitors once persistent infection had been established (FIG. 4D),providing additional evidence that persistent infection is insensitiveto CD8⁺ T cell immunity, even when the ability of the virus to preventMHC-I presentation is compromised.

Applicants' data imply that T cell evasion is not required forestablishment of primary CMV infection or once the sites of persistence(e.g., kidney and salivary gland epithelial cells) have been occupied,but rather it is essential to enable CMV to reach these sites ofpersistence from the peripheral site of inoculation in the CMV-immunehost. One possible scenario is that viral infection of circulatingcells, for example, monocytes, may succeed only if the virus preventselimination of these cells by virus-specific CTLs. More work, however,will be required to identify the cell type supporting superinfection.

Although the biochemical and cell biological functions of US2, US3, US6,and US11 have been studied extensively (C. Powers et al. Curr. Top.Microbiol. Immunol. 325, 333 (2008)), their role in viral pathogenesishad remained enigmatic. Analogous gene functions in murine CMV (MCMV)had been similarly found to be dispensable for both primary andpersistent infection (A. K. Pinto, A. B. Hill, Viral Immunol. 18, 434(2005)), although reduced viral titers have been reported for MCMVdeleted for these genes (A. Krmpotic et al., J. Exp. Med. 190, 1285(1999)). Thus, the reason all known CMVs dedicate multiple gene productsto MHC-I downregulation had remained elusive. Applicants' currentresults now identify a critical role for these immunomodulators toenable superinfection of the CMV-positive host. Furthermore, theseresults suggest that the ability to superinfect is an evolutionaryconserved function among CMVs and therefore might play an important rolein the biology of these viruses. Superinfection could promote themaintenance of genetic diversity of CMV strains in a highly infectedhost population, which could provide an evolutionary advantage. However,there is another possibility. CMV is a large virus with thousands ofpotential T cell epitopes and therefore a high potential for CD8⁺ T cellcross-reactivity (L. K. Selin et al., Immunol. Rev. 211, 164 (2006)).Indeed, in a study of pan-proteome HCMV T cell responses, 40% of HCMVseronegative subsets manifested one or more cross-reactive CD8⁺ T cellresponses to HCMV-encoded epitopes (A. W. Sylwester et al., J. Exp. Med.202, 673 (2005)). As CMV recognition by cytotoxic T cells appears toeffectively block primary CMV infection, individuals with cross-reactiveCD8⁺ T cell immunity might be resistant to CMV. Thus, US2-11 functionmay be necessary to evade such responses and establish infection in thislarge population of individuals that might otherwise be CMV-resistant.

Applicants' results also may explain why, so far, it has not beenpossible to develop a vaccine that efficiently protects humans from HCMVinfection. Although antibody-mediated mucosal immunity might reduce therate of superinfection (S. A. Plotkin et al. J. Infect. Dis. 159, 860(1989) and L. K. Selin et al., Immunol. Rev. 211, 164 (2006)), once thislayer of defense is breached, CMV-specific CTLs seem to be unable toprevent viral dissemination, due to MHC-I down-regulation by US2-11.Thus, although CMV vaccines might be able to limit CMV viremia andassociated morbidity, this MHC-I interference renders it unlikely thatsterilizing protection against CMV infection is an achievable goal.

Antibodies.

The following antibodies were used for immunoblots: anti-Gag Ab from theNIH AIDS Repository for all SIVgag expressing RhCMV recombinants oranti-FLAG (Sigma) for FLAGtagged SIVgag; anti-V5 (Invitrogen) forV5-tagged SlVretanef and anti-calreticulin (SPA-601, StressGen) forcontrol. Anti-RhCMV-IE1 was described previously (S. G. Hansen et al.,Nat Med 15, 293 (2009)). The following antibodies used in flow cytometrywere from BD Bioscience: L200 (CD4; AmCyan); SP34-2 (CD3; Alex700,PacBlu); SK1 (CD8alpha; TruRed); DX2 (CD95; PE); 25723.11 (IFN-γ; APC);6.7 (TNF; FITC). The following antibodies were obtained from BeckmanCoulter: CD28.2 (CD28; PE-Texas Red); L78 (CD69; PE).

Construction of Recombinant RhCMV.

All recombinant viruses used in this study were derived from strainRhCMV 68-1 (S. G. Hansen et al. J Virol 77, 6620 (2003)) and aregraphically depicted in FIG. 5. RhCMV(gagL) was generated by replacingthe loxP-flanked enhanced green-fluorescent protein (EGFP) in RhCMV-EGFP(W. L. Chang et al. J Virol 76, 9493 (2002)) with a loxP-flankedexpression cassette for SIVmac239-gag under control of the EF1α-promoterby in vivo recombination in tissue culture. All other recombinantviruses were created using the RhCMV bacterial artificial chromosome(RhCMV-BAC) (W. L. Chang, P. A. Barry, J Virol 77, 5073 (2003)) (FIG.5). The BAC-cassette was inserted between the RhCMV homologs of US1 andUS2 and self-excises via Cre-recombinase (W. L. Chang, P. A. Barry, JVirol 77, 5073 (2003)). Recombinant virus RhCMV(gag) contains acodon-optimized, FLAG-tagged SIVmac239-gag sequence under control of theEF1α-promoter inserted between ORFs R213 and 8214 (S. G. Hansen et al.,Nat Med 15, 293 (2009)). Deletion of the US2-11 region by homologousrecombination (ET cloning) with an FRT-flanked Kanamycin-resistance(KanR) cassette was described previously (C. J. Powers, K. Früh, PLoSPathog 4, e1000150 (2008)). ΔUS2-11(gag) was created by replacing theentire Rh182-189 region (base pairs 184489-191243) using the sameprimers and mutagenesis strategy as before (C. J. Powers, K. Früh, PLoSPathog 4, e1000150 (2008)) except that the inserted fragment harboredboth the KanR cassette and the codon-optimized, FLAG-taggedSIVgag-cassette. The KanR-cassette was removed by arabinose-inducedFLP-expression (C. J. Powers, K. Früh, PLoS Pathog 4, e1000150 (2008)).ΔVIHCEΔUS2-11(gag) was created by subsequent deletion of Rh178 (VIHCE;base pairs 181320-182060). Since ΔUS2-11(gag) contains a single FRTrecombination site from KanR-excision, Applicants used a KanR cassetteflanked by the F5-mutant FRT sequence for deletion of VIHCE. Thisprevents potential recombination between new and existing FRT sites whencreating dual-recombinants. The mutant FRT-flanked KanR cassette wasobtained from plasmid pOri6K-F5 (E. M. Borst, M. Messerle, J Virol 79,3615 (2005)) using primers5′-TAAAAGTGTCGGATGAATGTGCGGCGCCAACACGCAGACCGAAAAGTGCCACCTGC AGAT-3′ and5′-GCCTGACTGATGACTAGTCATCGCACGCCTCTTCCCGCCCCAGGAACACTTAACGGC TGA-3′.ΔVIHCE was created by replacing base pairs 181320-182060 with the SIVgagexpression cassette using primers 5′-TTTGTTCGTATAAAAGTGTCGGATGAATGTGCGGCGCCAACACGCAGACCGTAAAACGACGGCCAGT-3′ and 5′-CGCTCCCTCGGCCTGACTGATGACTAGTCATCGCACGCCTCTTCCCGCCCGTATGTTGTGTGGAATT GTGAG-3′.ΔRh186-8(retanef) was created from previously described V5-taggedRhCMV(retanef) (S. G. Hansen et al., Nat Med 15, 293 (2009)) by deletionof base pairs 187934-190031 using the KanR-cassette flanked by theF5-mutant FRT sites. All recombinant BACs were verified for correctdeletions by restriction digest, southern blot and sequence analysis ofthe insert-borders. RhCMV virus was reconstituted by electroporation oftelomerized rhesus fibroblasts (TRFs) (V. Kirchoff et al. Arch Virol147, 321 (2002)).

Characterization of recombinant viruses by RT-PCR. Resulting viruseswere plaque-purified and characterized for gene expression of deletedand flanking genes by RT-PCR (FIG. 8). TRFs were infected at MOI=1 andtotal RNA was collected at 24 hpi using RNeasy mini kit (Qiagen)according to the manufacturer's instructions. 4 μg of RNA was treatedwith DNAse I (Applied Biosystems) for 30 min at 37° C. 1 μg ofDNAse-treated RNA was used in a 20 μl reverse transcription reactioncontaining 50 ng random hexamers, 0.5 mM dNTPs, 10 mM DTT, and 1 μlsuperscript III RT in 1×RT buffer (Invitrogen) for 1 hour at 37° C. 1 μlof the RT reaction was used for semi-quantitative PCR with Platinum taqpolymerase (Invitrogen) under the following conditions: 1× platinum taqbuffer, 1.5 mM MgCl₂, 0.2 mM dNTPs, 0.5 μM each primer, and 1.5 Upolymerase. 35 cycles of amplification was performed under the followingconditions: 94° C. for 30 sec, 55° C. for 30 sec, and 72° C. for 15 sec.The following primer pairs were used: SIVgag 5′-ACCCACAACCAGCTCCACAA-3′and 5′-ATCCACTGGATCTGTTCGTCAA-3′; Rh156 5′-CAATGAGGATAGGTTCCCAGTTG-3′and 5′-GCCAGTGGGATGTCAGTACCA-3′; Rh175 5′-CTAGCAGTACTGAGAGCTAG-3′ and5′-TCACGCCAATCGACAGTGCACG-3′; Rh178 5′-CGCATACTGACAAGCCAGGGC-3′ and5′GCGAAAGAAGGTGCACATGAC-3′; Rh181 5′-CCTTACGGAGTCGCTCGTTGAC-3′ and5′-TGTGTCGTCTCTTTCTCCGCAG-3′; Rh182 5′-GATTTTCGTTGAACATGTCCGAC-3′ and5′-GTTATGTGTCAGAAAGTCCG GCT-3′; Rh189 5′-TGCTTCGTCCTGGTGCTGT-3′ and5′-TTAGCAGTTTCATGGTTG CGA-3′; Rh190 5′-GAAATGGATAGCGGTGCTCAC-3′ and5′-CAGACAACAGGTTG TTCAGG-3′; GAPDH 5′ 5′-GCACCACCAACTGCTTAGCAC-3′ and5′-TCTTCTGGGTGG CAGTGATG-3′. For characterization of theRhΔ186-8(retanef) virus, RT-PCR was performed as described above withthe following primer pairs: Rh185 5′-AGCGTAGCTCCTCCATACCG CT-3′ and5′-ATCCGCGGACTGTTTGGGTGT-3′; Rh186 5′-GCTTCTTCCAGAAGTTGCA TAGGATGA-3′and 5′-CGACTTTCCGGATCCTACGTGGC-3′; Rh187 5′-CCATAGCCATGCAATGGTCGCA-3′and 5′-GCGCCATCCCGTGTTACCCC-3′; Rh188 5′-AGAGCTCTGGTCGTCGGCGT-3′ and5′-TGGCTGGCCACCAGATGGATGT-3′; Rh189 5′-AACCAGTAGGAGCGCCCGGT-3′ and5′-CGACTCCTGCATGCTTACTGGGGA-3′; β-actin 5′-TCACCCACACTGTGCCCATCTACGA-3′and 5′-CAGCGGAACCGCTCATTGCCAATGG-3′.

Characterization of recombinant viruses by comparative genomesequencing. To confirm that the genetic manipulation of the RhCMV genomedid not introduce unwanted mutations outside the regions targeted fordeletion, Applicants used Comparative Genome Sequencing (CGS) to comparethe deletion viruses against RhCMV-BAC. Single nucleotide differencesbetween reference and test strains of herpesviruses may be identifiedwith CGS (O. Timoshenko et al. J Med Virol 81, 511 (2009) and D. Estepet al. J Virol 81, 2957 (2007)). CGS of viral DNA was performed using amicroarray hybridization-based technique with services provided byNimbleGen Systems, Inc. (Madison, Wis.). A RhCMV comparative genomichybridization array was created using the published sequence for RhCMV68.1 (S. G. Hansen et al. J Virol 77, 6620 (2003)). Oligonucleotidesthat comprised this array were designed to be between 29 and 32 bp, withoverlapping sequences of at least 7 bp, with coverage of both strands ofthe RhCMV 68.1 genome. Viral DNA was isolated using standard methodsfrom a) parental RhCMV-BAC (W. L. Chang, P. A. Barry, J Virol 77, 5073(2003)), b) ΔVIHCEΔUS2-11(gag), c) ΔUS2-11(gag), or d) ΔVIHCE(gag).Briefly, virus was produced in telomerized rhesus fibroblasts (TRFs),supernatants were collected and, after proteinase K treatment, DNA wasisolated by cesium chloride gradient centrifugation. The resulting viralDNA was ethanol precipitated and brought to a final concentration of 1μg/μl. Viral DNA was fragmented and labeled with Cy3 (RhCMV-BAC asreference) or Cy5 (deletion viruses). Labeled reference and test viralDNA probes were co-hybridized to the tiling arrays and the Cy3 and Cy5signals were scanned. SignalMap software (NimbleGen Systems, Inc.) wasused to analyze all CGS data.

Rhesus Macaques.

A total of 28 purpose-bred juvenile and adult male rhesus macaques (RM)(Macaca mulatta) of Indian genetic background were used in this study,of which four animals were specific pathogen-free (SPF) animals andlacked RhCMV-specific T cells and antibodies. All other animals used inthe study acquired RhCMV naturally while in the colony. The presence orabsence of RhCMV-specific T cell responses was confirmed byintracellular cytokine staining of RhCMV Ag-stimulated PBMC (Table 1).All RM were free of cercopithicine herpesvirus 1, D-type simianretrovirus, simian T-lymphotrophic virus type 1 and SIV infection.Animal protocols were approved by the Oregon National Primate ResearchCenter Animal Care and Use Committee, under the standards of the USNational Institutes of Health Guide for the Care and Use of LaboratoryAnimals. Animals were inoculated with 10²-10⁷ PFU of recombinant virussubcutaneously. For CD8+ cell depletion, RM were treated with 10, 5, 5and 5 mg per kg body weight of the humanized monoclonal antibody cM-T807(J. E. Schmitz et al., Am J Pathol 154, 1923 (1999)) one day beforeviral infection and on days 2, 6, and 9 post infection, respectively.

Virological Analysis of Rhesus Macaques.

Isolation and co-culture of virus from urine and buccal swabs wasperformed as described previously (S. G. Hansen et al., Nat Med 15, 293(2009)). Briefly, virus was concentrated from cleared urine andco-cultured with rhesus fibroblasts and cell lysates were collectedafter cytopathic effects were observed or after 28 days.

PCR Analysis of Co-Cultured Virus.

Supernatant from cells prepared from urine co-cultures was used toinfect fresh TRFs. When the cells reached 90-100% cytopathic effect,total DNA was collected. Cells were scraped and lysed in 300 μl of abuffer containing 10 mM Tris-HCl, pH 8.5, 5 mM EDTA, 0.2M NaCl, and 0.2%SDS for 5 minutes at 60° C., followed by addition of 10 μg RNAse A and 5μl proteinase K (Fermentas, ˜20 mg/mL) for 1 hour at 60° C. Protein wasthen precipitated with 150 μl of 5M NaCl and incubated on ice for 5 min.Debris was pelleted at 16000×g for 15 min, supernatant removed, and DNAprecipitated with 450 μl isopropanol. 50 ng of DNA was used for PCRanalysis under the following conditions: 1× platinum taq buffer, 1.5 mMMgCl₂, 0.2 mM dNTPs, 0.5 μM each primer, and 1.5 U platinum taqpolymerase. 35 cycles of amplification was performed under the followingconditions: 94° C. for 30 sec, 55° C. for 30 sec, and 72° C. for 80 sec.The following primer pairs were used: Rh156 5′-GTTTAGGGAACCGCCATTCTG-3′and 5′-GTATCCGCGTTCCAATGCA-3′; SIVgag 5′-ACCCACAACCAGCTCCACAA-3′ and5′-CTGCCATTAATCTAGC-3′; Rh189 5′-CTCTGGTCGTCGGCGTATG-3′ and5′-TGCTTCGTCCTGGTGCTGT-3′; Rh180 5′-GGCAAGGGAGCTCAATGGAAAC-3′ and5′-TCAACGCCCATCTAAAGCCG-3′; Rh178 5′-CGTTTGCTTCCTATGTCCGC-3′ and5′-CATTTGCATGCAGCTGTGCG-3′.

Immunological Analysis of Rhesus Macaques.

Collection of BAL was performed as described previously (C. J. Pitcheret al., J Immunol 168, 29 (2002)). CD4+ and CD8+ T cell responses weremeasured by flow cytometric intracellular cytokine analysis of PBMC andBAL cells, as previously described (S. G. Hansen et al., Nat Med 15, 293(2009)). For T cell stimulation assays RhCMV lysates (68-1 strain) oroverlapping 15mer peptides representing the SIVmac239 Gag, Rev/Tat/Nefproteins or the RhCMV Immediate Early-1 and 2 proteins (overlap=11 aminoacids), were used in the presence of co-stimulatory mAbs CD28 and CD49d(BD Biosciences). Co-stimulation in the absence of antigen served as abackground control. Cells were incubated with antigen and thecostimulatory molecules alone for 1 hr, and then in the presence of thesecretion inhibitor Brefeldin A (10 μg/ml; Sigma Aldrich) for anadditional 8 hrs. After surface and intracellular staining withconjugated mAbs, polychromatic (6 to 8 parameter) flow cytometricanalysis was performed on an LSR II Becton Dickinson instrument. Listmode multi-parameter data files were analyzed using the FlowJO softwareprogram (version 8.8.6; Tree Star, Inc.). Using this software CD3′ cellswere divided into CD4+ and CD8+ T cells subsets, and then analyzed for asubset manifesting up-regulation of the activation marker CD69 andcytokine, either TNFα alone (FIG. 1 data), or TNFα and/or IFN-γ (FIGS.2-4 data) (see FIG. 6). For PBMCs, this background-subtracted value wasdivided by the fraction of total memory cells (determined as describedbelow) to achieve the reported “memory corrected” response frequency (C.J. Pitcher et al., J Immunol 168, 29 (2002)). For BAL, the reportedresponses were background response (no antigen) subtracted only, as BALT cells are entirely memory cells. (C. J. Pitcher et al., J Immunol 168,29 (2002)). To determine the memory fraction of circulating T cells,memory and naive T cell subset populations were delineated based on CD28and CD95 expression patterns, as described in (C. J. Pitcher et al., JImmunol 168, 29 (2002)) (see FIG. 7).

Example 2

In this Example, Applicants develop a number of attenuatedRhCMV-vaccines to examine the highest level of attenuation that maystill achieve protection against ΔUS2-11-Gag. A limitation ofApplicants' preliminary data was that Applicants had only shown thatnatural infection with RhCMV was protective against re-infection withΔUS2-11, but Applicants had yet to demonstrate that experimentalinfection with recombinant RhCMV would be protective. Applicants nowdemonstrate that a recombinant virus lacking the major tegument proteinspp65a and pp65b or pp71 protects against re-infection by ΔUS2-11-Gag.

PP65 is one of the most abundant proteins in HCMV particles and the mostabundant component of the viral tegument, an amorphous protein structurelayered between the capsid and the envelope. In addition to its role inevading innate immune responses, pp65 is one of the most immunogenicproteins encoded by HCMV and it is therefore included in mostexperimental vaccines and pp65-specific T cells are routinely includedin adoptive transfer protocols. However, the role of pp65 for acute andpersistent infection in vivo has never been examined.

RhCMV encodes two homologues of HCMV pp65 (UL83), pp65a (Rh111) andpp65b (Rh112). Using BAC-mutagenesis, Applicants deleted Rh111 and Rh112from the RhCMV genome. ΔRh111-2 does not show a growth defect infibroblast cultures (data not shown). Applicants infected twosero-negative animals with 5×10⁶ pfu of ΔRh111-2. Infection wasmonitored immunologically over the following months (FIG. 10). Bothanimals developed a robust CMV-specific CD4+ T cell response as measuredby intracellular cytokine staining. In contrast to animals infected withWT-RhCMV (a representative animal is shown in FIG. 10), neither of theΔRh111-2-infected animals developed an immune response to pp65. Toexamine whether the anti-CMV immune response of two ΔRh111-2-infectedanimals was comparable to natural infection with respect to protectionagainst ΔUS2-11-deleted virus, Applicants inoculated 10⁷ pfu ofΔUS2-11-Gag s.c. and monitored the Gag-specific immune response.However, neither of the animals developed a CD4+ or CD8+ T cell responseto Gag in PBMC whereas they remained positive for IE (FIG. 11, shown arethe average responses).

Surprisingly, pp65 does not seem to be required for primary infection ofCMV-naïve animals by RhCMV. These data further demonstrate thatexperimental infection with recombinant RhCMV may protect againstre-infection with ΔUS2-11. Interestingly, ΔUS2-11-protective T cellimmunity does not seem to depend on pp65-specific T cells despite itsimmunodominance during natural infection in both human and rhesus CMV.

RhCMV/SIV vectors may 1) establish persistent infection inRhCMV-seropositive rhesus macaques (RM), 2) elicit potent, long-lastingSIV-specific CD4+ and CD8+ T cell responses with a strong “effectormemory” (T_(EM)) bias (see FIG. 16), and 3) protect ˜50% of vaccinatedRM from progressive SIV infection after limiting dose, intra-rectalchallenge with the highly pathogenic SIVmac239 virus (see FIG. 10). Theprotection manifested in RhCMV/SIV vaccinated RM is distinct fromprevious T cell SIV vaccines in its abruptness and extent, withprotected RM manifesting a viral burst in plasma of varying size uponinitial infection, followed by immediate control to undetectable levels.While these RM may subsequently show periodic, low level “blips” ofviremia, CD4+ memory depletion is not observed and SIV-specific antibody(Ab) responses do not boost, indicating a very high level of control.Moreover, to date, this stringent control has been stable for >30 weeksin 16/17 protected RM. Protection correlates with peak totalSIV-specific CD8+ T cell responses in blood during the vaccine phase,which likely reflects the degree to which these cells are seeded intoeffector tissues. Taken together, these data indicate a novel pattern ofprotection consistent with very early control, likely occurring at thesite of viral entry or early sites of viral replication andamplification, and mediated by tissue-resident CD8+ T_(EM).Significantly, the epitope targeting of RhCMV-vectored SIV-specific CD8+T cell responses is distinct from responses elicited by conventionalviral vectors or SIV itself: RhCMV-vectored CD8+ T cells target a broadarray of (likely cross-presented) epitopes that exclude the typicalimmunodominant epitopes (e.g., CM9 or TL8 in Mamu A*01+ RM) that areinternally processed in and presented by virally infected cells (seeFIG. 20). This differential CD8+ T cell targeting of wildtype (wt) RhCMVvectors is mediated by the activity of RhCMV genes that inhibit class IMHC-restricted Ag presentation (US2-11 homologues), as US2-11 deletantRhCMV vectors elicit CD8+ T cell responses that include prominentresponses to the conventional SIV epitopes (see FIGS. 17, 19 and 20). Inthis Example, Applicants define the immunobiology of RhCMV/SIVvector-mediated protection, including the mechanisms, timing andlocation of protection, and the impact of differential CD8+ T epitopetargeting on the efficiency of SIV control, in particular asking whetherbroadening RhCMV/SIV-vectored CD8+T cell responses to include typicaldominant epitopes may improve response quality and enhance efficacy. Thegoals of this Example are:

The differential epitope targeting patterns and breadth of SIV-specificCD8+ T cells elicited by wt vs. (MHC I-down-regulation-null)US2-11-deletant RhCMV/SIV vectors is hypothesized to correlate withtheir breadth and efficacy; US2-11 deletant vectors directvector-elicited CD8+ T cell responses to include typical internallyprocessed epitopes (see FIGS. 19 and 20). Such vectors might thereforehave enhanced efficacy against limiting dose intra-rectal SIVmac239challenge compared to wt vectors. By homology, US2-11 deletedHCMV-vectors carrying HIV antigens are expected to induce a broader Tcell response to HIV epitopes which might correlate with betterprotection

HIV infections of humans and SIV infections of Asian macaques share apattern of viral replication and a constellation of pathologic featuresthat in the absence of effective anti-retroviral therapy results inunremitting infection, and progressive, ultimately fatal,immunodeficiency in the vast majority of infected individuals (Levy, J.A. 1993. Microbiol Rev 57:183-289. Grovit-Ferbas, K. et al. 1999. HumanImmunodeficiency Virus. In Persistent Viral Infections. R. Ahmed, and A.I. Chen, editors. Chicester: John Wiley & Sons. 3-45, Douek, D. C. etal. 2003. Annu Rev Immunol 21:265-304, Grossman, Z. et al. 2006. Nat Med12:289-295, McChesney, M. et al. 1999. Simian Immunodeficiency Virus. InPersistent Viral Infections. R. Ahmed, and I. S. Chen, editors.Chichester: John Wiley & Sons. 321-345 and Cohen, O. J., and Fauci, A.S. 2001. Pathogenesis and Medical Aspects of HIV-1 Infection. In FieldsVirology. D. M. Knipe, and P. M. Howley, editors. Philadelphia:Lippincott Williams & Wilkins. 2043-2094). A striking feature of theseinfections is their induction of robust cellular and humoral immunity,which fails to clear or, in most subjects, even effectively controlviral replication. HIV/SIV adaptations that provide for efficient immuneevasion include 1) massive replication, high mutation rates, geneticmalleability and functional plasticity leading to rapid evolution, 2)specific genetic mechanisms to thwart innate and adaptive immunemechanisms (e.g., countering tetherin, APOBEC, Trim5α innate anti-viralmechanisms and cytotoxic T cells by class 1 MHC down-regulation), 3) envadaptations to avoid antibody (Ab) neutralization, 4) latency, and 5)dysregulated immune function (Evans, D. T., and Desrosiers, R. C. 2001.Immunol Rev 183:141-158, Johnson, W. E., and Desrosiers, R. C. 2002.Annu Rev Med 53:499-518, Goulder, P. J., and Watkins, D. I. 2008. NatRev Immunol 8:619-630, Malim, M. H., and Emerman, M. 2008. Cell HostMicrobe 3:388-398 and Frost, S. D. et al. 2008. Curr Opin HIV AIDS3:45-51). These mechanisms pose an imposing set of challenges fordeveloping an effective HIV/AIDS vaccine, but fortunately, it isincreasingly clear that HIV/SIV do have immune vulnerabilities. CD8+ Tcell responses, and to a lesser extent, Ab responses may modulate viralreplication, and in certain circumstances may manifest sufficientanti-viral activity to control, albeit not eliminate, infection(Goulder, P. J., and Watkins, D. I. 2008. Nat Rev Immunol 8:619-630,Frost, S. D. et al. 2008. Curr Opin HIV AIDS 3:45-51, Baker, B. M. etal. 2009. Expert Opin Biol Ther 9:55-69 and Goonetilleke, N. et al.2009. J Exp Med 206:1253-1272). In HIV/SIV infections of naïve subjects,most adaptive immune responses develop only after substantial systemicviral replication has already occurred, and therefore, for theseresponses to manifest virologic control, they must be of superlativepotency and/or have optimal epitope targeting to prevent viral evolutionand escape. However, there is increasing evidence that the initial viralbridgehead in the first few days after mucosal exposure, made by one ortwo viral species (Keele, B. F. et al. 2008. Proc Natl Acad Sci USA105:7552-7557), is much more vulnerable. At this stage, immunity wouldact on a much smaller, less diverse and localized viral population, andif such responses could suppress the viral reproductive ratio (R₀) to<1, the infection may fail to establish altogether (Haase, A. T. 2005.Nat Rev Immunol 5:783-792). Indeed, increasing evidence suggests thatimmunity has the potential to prevent and/or stringently control HIV/SIVinfection, but the window of opportunity for this high level protectionis almost certainly both early and short.

The association of elite HIV/SIV control in humans and non-humanprimates (NHP) with CD8+ T cell responses targeting particular epitopesrestricted by specific class I MHC alleles led to the hypothesis that avaccine capable of eliciting strong and broadly targeted virus-specificCD8+ T cell memory might, upon infection, bring to bear sufficientimmunologic pressure on vulnerable viral sequences to suppress viralreplication and/or force genetic changes resulting in reduced viralfitness (Walker, B. D., and Burton, D. R. 2008. Science 320:760-764 andWatkins, D. I. et al. 2008. Nat Med 14:617-621). While not expected toprevent infection, it was hypothesized that such a vaccine-elicited Tcell response would reduce median peak and plateau-phase viral loads inthe population, and thereby, on average, slow pathogenesis, and reducethe likelihood of transmission. In the past few years, this concept hasbeen extensively evaluated in the Indian-origin RM/SIVmac model usingincreasingly potent vectors and prime-boost combinations, and a varietyof challenge routes and doses. The general conclusions from thesestudies are that, compared to naïve RM, the best vaccine regimens mayindeed reduce peak and plateau-phase viral loads of highly pathogenicSIVmac viruses and extend survival. However, protection is 1) unevenwithin identically vaccinated RM cohorts (and often correlated withprotective MHC alleles), 2) seemingly limited to ˜1.5-2 log meanreduction in peak and plateauphase plasma viral loads with SIVmacchallenge, and 3) subject to reversion over time (18-29). This patternof protection is similar for intravenous, high (single) and low(repeated) dose mucosal challenge, and appears to derive from a massiveanamnestic CD8+ T cell response after infection that “intercepts” viralreplication fairly late during systemic spread, with anti-viral activityfirst manifested by a blunting of peak SIV replication at day 10 to 14.As illustrated in FIG. 12, the CD8+ memory T cells that result fromprime-boost vaccines with non-replicating vectors are dramaticallyexpandable upon infection, but the proliferation, differentiation andeffector cell delivery to viral replication sites is quite delayedrelative to viral kinetics, a temporal relationship that clearly limitsboth the extent and durability of protection. Indeed, the first test ofthis concept in humans, the phase 2b Merck STEP trial (HVTN 502), was aclear failure. Despite detection of HIV-specific CD8+ T cells in 73% ofvaccinees, there was no evidence of protection in terms of infectionacquisition or post-infection viral replication (Buchbinder, S. P. etal. 2008. Lancet 372:1881-1893, McElrath, M. J. et al. 2008. Lancet372:1894-1905). The STEP regimen may, in retrospect, have beeninsufficiently potent (or unable to elicit a sufficiently broadHIV-specific CD8+ T cell response) to achieve significant protection,but the results clearly illustrate the difficulty in attainingmeaningful efficacy with a vaccine designed to elicit conventional CD8+memory T cells.

If conventional vaccine-elicited T cell memory (memory responses that,upon initial pathogen encounter, require effector expansion,differentiation and migration to mediate anti-viral activity) intervenestoo late in HIV/SIV infection, the alternative is a vaccine designed toelicit and maintain “effector memory” T cells (T_(EM)). T_(EM) lackrobust expansion capacity, but are localized in effector sites andpoised for immediate effector function (Bannard, O. et al. 2009. Eur JImmunol 39:2083-2087, Hansen, S. G. et al. 2009. Nat Med 15:293-299,Sallusto, F. et al. 2004. Annu Rev Immunol 22:745-763, Picker, L. J. etal. 2006. J Clin Invest 116:1514-1524, Pitcher, C. J. et al. 2002. JImmunol 168:29-43 and Genesca, M. et al. 2009. J Intern Med 265:67-77).Indeed, CD4+ T_(EM) are the primary targets of HIV/SIV (Grossman, Z. etal. 2006. Nat Med 12:289-295), and as CD4+ and CD8+ T_(EM) cohabit thesame sites, a vaccine-generated CD8+ T_(EM) response would theoreticallybe ideally positioned to intercept initial/early viral replication inprimary infection, providing anti-viral effector activity during themost vulnerable phase of infection. Long-term maintenance of T_(EM)populations is associated with persistent Ag, and conversely, apronounced T_(EM) bias characterizes T cell responses tochronic/persistent agents, in particular CMV (Hansen, S. G. et al. 2009.Nat Med 15:293-299, 35, 38-40). Applicants therefore initiated a RhCMVvector development program to assess the ability of T_(EM) to interveneearly in primary SIV infection. As recently described (Hansen, S. G. etal. 2009. Nat Med 15:293-299, Picker, L. J., Reed-Inderbitzin, E. F.,Hagen, S. I., Edgar, J. B., Hansen, S. G., Legasse, A., Planer, S. etal. 2006. J Clin Invest 116:1514-1524, Gauduin, M. C. et al. 2006. J ExpMed 203:2661-2672, Kern, F. et al. 1999. Eur J Immunol 29:2908-2915,Champagne, P. et al. 2001. Nature 410:106-111), RhCMV may be modified tohighly express SIV proteins, without disruption of other RhCMV genes,and with preservation of wildtype growth characteristics (in vitro andin vivo). These vectors may re-infect RhCMV-seropositive RM in aclinically silent manner, and in the process of re-infection elicitindefinitely persistent, high frequency CD4+ and CD8+ T cell responsesagainst the SIV gene products. These RhCMV-vector elicited SIV-specificT cell responses manifest a polyfunctional, highly T_(EM)-biasedphenotype, and in keeping with this phenotype were highly enriched ineffector sites [(Hansen, S. G. et al. 2009. Nat Med 15:293-299); and seeFIG. 16]. RhCMV/SIV vectors do not elicit significant SIV-specific Abresponses, nor do they appear even to prime for such responses (Hansen,S. G. et al. 2009. Nat Med 15:293-299). In the first efficacy assessmentof these vectors, RM immunized with RhCMV/gag, /rev/nef/tat, and /envwere challenged with repeated, limiting dose intra-rectal SIVmac239 at486-615 days after the last vaccination. This challenge protocol wasdesigned to infect RM via mucosal exposure with viral doses more akin tosexual HIV transmission in humans (24). Applicants found that 4/12vaccinees (vs. 0/16 controls) were demonstrably infected with SIV butcompletely controlled infection, to the extent that CD8+ cell depletionfailed to elicit viral recrudescence (Hansen, S. G. et al. 2009. Nat Med15:293-299). As described in detail below, these initial results havebeen confirmed and extended in a second large RM efficacy using the samerepeated, limiting dose SIVmac239 challenge. Overall, ˜50% ofRhCMV/SIV-vaccinated RM have been highly protected from progressive SIVinfection after intra-rectal challenge with highly pathogenic,CCR5-tropic SIV.

Worldwide in 2007, there were ˜2.5 million new HIV infections, over 33million people living with HIV and 2.1 million AIDS deaths (2008 UNAIDSReport). In southern Africa, adult prevalence rates may exceed 15%. Aneffective prophylactic vaccine would have a tremendous impact on theepidemic, and is likely the only way it may be conquered. As discussedabove, HIV is an extremely difficult vaccine target, and an effectiveHIV/AIDS vaccine most likely has to include multiple components, eachdesigned to exploit different viral immune vulnerabilities and acting atdifferent stages of primary infection (FIG. 13). CMV vectors (and the“T_(EM)” vaccine concept) offer a powerful new addition to this vaccine“arsenal”, and it thus becomes a high priority to both define themechanism(s) by which these vectors protect and optimize their efficacy.This information is critical for the “translation” of CMV vectors intothe clinic, as well as for developing other modalities that wouldutilize or enhance the same protective mechanism(s). It should also beemphasized that the early protection mediated by CMV vector-elicitedresponses offers both a new window to explore and a new means toexperimentally manipulate early HIV/SIV-immune system interactions.Thus, the understanding of T_(EM) biology and mechanisms by which CMVvector-elicited T_(EM) protect sheds light on the crucial early eventsthat follow mucosal HIV/SIV infection. This Example addresses thesepriorities by providing detailed analysis of 1) the distribution andfunctional characteristics of RhCMV vector-elicited, SIV-specific Tcells and the relationship between these characteristics and efficacy,2) where and how these responses “intercept” and suppress mucosallyadministered SIV in primary infection, and control SIV replication overthe long-term, and 3) the differential CD8+ T cell epitope targetingmediated by US2-11 gene function in wt vs. mutant CMV/SIV vectors, andthe impact of this differential targeting on efficacy.

Applicants have accomplished all of the above goals, includingconstruction, optimization, and selection of RhCMV vectors expressingSIVgag, rev/nef/tat, env and pol, extensive assessment of vector biologyand immunogenicity, and most importantly, efficacy assessment anddelineation of immune correlates. The hypothesis that RhCMV vectors andthe T_(EM) responses they elicit may be efficacious against highlypathogenic SIV has been confirmed, and a new pattern of early protectionhas been discovered. The details of these accomplishments are describedin Hansen, et al. (Hansen, S. G. et al. 2009. Nat Med 15:293-299).

Applicants followed the promising results of Applicants' first efficacyassessment of RhCMV/SIV vectors (Hansen, S. G. et al. 2009. Nat Med15:293-299) with a larger trial that included 4 arms: A) RhCMV/gag,RhCMV/env, RhCMV/rev/nef/tat, RhCMV/pol-1, and RhCMV pol-2 (wks 0, 14),B) the same RhCMV/SIV vectors (wk 0) followed by pan-proteome Ad5/SIVvectors (wk 14), C) pan-proteome DNA (wks, 0, 4, 8) followed bypan-proteome Ad5 vectors (wk 14), and D) additional unvaccinatedcontrols. These RM were challenged with same repeated, limiting dose,intra-rectal SIVmac239 regimen as Applicants' first study, withchallenge initiated at wk 58. The results of this trial wereunprecedented (FIG. 10). Of the 24 RM that received an RhCMV/SIVvector-containing regimen (Groups A and B), 13 (54%) manifested initialSIVmac239 infection with a variably sized blip/burst of plasma viremia,which was followed by immediate control to undetectable levels. None of9 DNA/Ad5-vaccinated RM manifested such control, and only 1 of 28unvaccinated RM manifested an initially occult infection (whichspontaneously reverted to progressive infection at wk 16). ProtectedRhCMV/SIV-vaccinated RM manifested variable numbers of low level viralblips at subsequent time points (FIG. 10), but overall viral control wassufficiently early and stringent to preclude any CD4+ target celldepletion (FIG. 11), as well as prevent induction (Group A) or boosting(Group B) of the anti-SIVenv antibody response (FIG. 12). Importantly,protection in both RhCMV vector-vaccinated groups significantlycorrelated with the magnitude of the peak total SIV-specific CD8+ T cellresponse in blood during the vaccine phase (FIG. 13), not the responsespresent immediately pre-challenge (and not SIV-specific CD4+ T cellresponses, not shown). These peak CD8+ responses in blood likely reflectthe degree to which CD8+ T_(EM) are seeded into systemic effector sitesduring vaccination. The RhCMV-vectored, SIV-specific T cell responseswere fundamentally different from the responses elicited by DNA/Ad5. Thelatter did not provide the immediate protection seen in the RhCMV/SIVvector-vaccinated RM, but did demonstrate significant mean reductions inpeak and early plateau-phase viral loads, and were associated withstrong boosting upon infection (FIG. 14). In contrast, the protectionassociated with RhCMV/SIV vectors alone was binary, providing eitherimmediate stringent control, or no control, and in keeping with this,these responses did not significantly boost in the unprotected(progressively infected) RM (FIG. 14). The RM given RhCMV/SIV andAd5/SIV vectors showed both the immediate “T_(EM)” protection, anelement of peak and post-peak (“T_(CM)”) control, and a post-infectionresponse boost, similar to, but less than, the DNA/Ad5-vaccinated group(FIG. 14). 12/13 of RhCMV vector-protected RM maintained stringentprotection for >30 weeks, whereas 7/9 DNA/Ad5-vaccinated RM wereindistinguishable from controls by 26 weeks post-infection.

Taken together, these results suggest that RhCMV-vectored SIV-specific Tcell responses intercept mucosally administered SIV infection very earlyin primary infection, prior to extensive systemic replication and maymaintain stringent control after this early “intercept”. On the otherhand, if the virus “wins” the initial battle and extensive, systemicreplication ensues, RhCMV/SIV-vectored T_(EM) responses are unable to“chase” and do not provide peak or post-peak protection. In Applicants'first study (Hansen, S. G. et al. 2009. Nat Med 15:293-299), Applicantsfound no evidence of persistent SIV infection in the 4 protected RM, andApplicants speculated that infection might have been aborted in thecolonic mucosa itself. In the follow-up study, however, Applicants havedocumented higher initial viral bursts in plasma, and have found in mostprotected RM a very low-level persistent infection (manifest byoccasional viral “blips”). Moreover, although cell-associated SIV iseither very low or negative in PBMC of most samples from protected RM(data not shown), Applicants have unequivocally documented SIV DNA- andRNA-positive CD4+ T cells in the blood of protected RM (those with thehighest initial viral bursts; FIG. 15), establishing that the SIVinfection is not wholly contained in the rectal mucosa after rectalchallenge, and protection must, at least in part, be systemic. Thesedata strongly suggest that there is an early extra-mucosal phase ofviral amplification and “broadcast”, which is a likely (additional)point of intercept between RhCMV-vectored, SIV-specific T_(EM) responsesand the developing SIV infection. In keeping with this, Applicants havefound that RhCMV/SIV vectors indefinitely maintain strikingly highfrequencies of SIV-specific T cells in target cell-rich effector sitesthat are likely candidates for initial viral infection andamplification, including both rectal mucosa and sites of potentialhematogenous viral spread—spleen, liver, bone marrow (FIG. 16). Smaller,but substantial frequencies of CMV-vectored, SIV-specific CD8+ T cellsare in mesenteric lymph nodes (LN; FIG. 16), another site of potentialviral spread. Applicants therefore hypothesize that this array of highfrequency SIV-specific (CD8+) T_(EM) responses constitutes a “shield”against early viral amplification, capable of arresting infection priorto progressive systemic infection.

During the course of evaluation of RhCMV/SIV vector immunogenicity,Applicants assessed the degree to which the CD8+ T cell responseselicited by these vectors recognized epitopes that had been previouslyshown to represent dominant targets in SIV-infected orDNA/Adenovirus/pox vector-vaccinated RM with the appropriate restrictingMHC class I allele. These epitopes included Mamu A*01-restrictedgag-CM9, -LW9, -VL8, -QI9, -VT10, -LF8, -LA9, env-TL9, and tat-SL8 (12RM); Mamu A*02-restricted gag-GY9, env-RY8, and nef-YY9 (4 RM); MamuB*08-restricted nef-RL10 (1 RM), and Mamu B*17-nef-IW9, -MW9, andenv-FW9 (7 RM) (41-44). Surprisingly, whether analyzed by tetramerbinding or intracellular cytokine staining (ICS), all these specificepitope responses were negative in RhCMV/SIV vaccinated RM, despitethese RM manifesting robust CFC-defined, CD8+ T cell responses to totalmixes of overlapping, consecutive 15mer peptides for the relevant SIVprotein (FIG. 17). The failure to identify these typical immunodominantCD8+ T cell responses was neither technical, nor related to individualmonkey peculiarities, as subsequent administration of Ad5/SIV vectors(or progressive SIV infection) in many of these RM was associated withthe appearance for these typical responses (FIG. 17, right panel). Thesedata indicate that RhCMV/SIV-vectored responses differ from DNA andconventional viral vectors (e.g., Ad5) not only in their T_(EM)-biasedphenotype, function, distribution and longevity, but also in their CD8+T cell recognition patterns.

HCMV encodes 4 related glycoproteins that act together to preventpresentation of MHC class I-restricted epitopes by infected cells: US2and US11 mediate the retrograde translocation of MHC-I molecules intothe cytosol for proteosomal degradation; US3 retains MHC-1 molecules inthe endoplasmic reticulum (ER); and US6 inhibits translocation of viraland host peptides across the ER membrane by the peptide transporter TAT(Powers, C. et al. 2008. Curr Top Microbiol Immunol 325:333-359. Liu, Z.et al. 2009. Int J Biochem Cell Biol 41:503-506, van der Wal, F. J. etal. 2002. Curr Top Microbiol Immunol 269:37-55 and Hewitt, E. W. et al.2001. EMBO J 20:387-396). RhCMV encodes sequence and functionalhomologues of these 4 proteins in a genomic region spanning Rh182 (US2)to Rh189 (US11) (Powers, C., and Fruh, K. 2008. Microbiol Immunol197:109-115 and Pande, N. T. et al. 2005. J Virol 79:5786-5798). Toassess the role of these proteins in RhCMV/SIV vector immunobiologyApplicants constructed vectors in which the US2-11 region wasspecifically deleted (Powers, C. J., and Fruh, K. 2008. PLoS Pathog4:e1000150). US2-11 knock-out (KO) RhCMV vectors readily infectedRhCMV-naïve RM (and manifest a virologically and immunologically“normal” primary infection), but were completely unable to re-infectRhCMV seropositive RM, unless CD8+ lymphocytes were depleted for atleast 2 weeks during vaccination (FIG. 18). Interestingly, in bothinitially RhCMV-naïve RM and CD8-depleted, seropositive RM, the KOvector infection was indefinitely persistent, even after the appearance(naïve) or re-appearance (CD8-depleted) of RhCMV-specific CD8+ T cellresponses. These data indicate a CD8+ cell-mediated checkpoint inre-infection that is bypassed by wt RhCMV via the function of theseclass I MHC Ag presentation inhibitory genes. While Applicants expectedthat loss of US2-11 gene product-mediated “protection” from cytolyticeffector T cells would have a virologic consequence, it was surprisingthat this consequence only manifested in re-infection, suggesting thatimmune evasion by this mechanism may have evolved to allowsuper-infection, or possibly, to prevent pre-existent, cross-reactiveCD8+ memory T cells (Sylwester, A. W. et al. 2005. J Exp Med202:673-685) from interfering with primary infection. Even moresurprising, however, was the effect of US2-11 deletion on CD8+ T cellresponse induction. In contrast to wt RhCMV/SIV vectors, theSIV-specific CD8+ T cell responses that developed during 1° infectionwith the US2-11 region KO vectors prominently targeted conventional MamuA*01-restricted immunodominant SIV epitopes (FIG. 19). The gag-specificCD8+ T cell responses generated by wt RhCMV/gag were very broadlytargeted, spanning all regions of the gag protein, but manifested a lackof reactivity with 15mer peptides containing the conventionalimmunodominant epitopes, creating distinct “holes” in the responsebreadth in Mamu A*01+RM (FIG. 20). In the gag-specific CD8+ T cellresponses elicited by the US2-11 KO RhCMV/gag vector, these “holes” werefilled, and the responses were even more broadly targeted. Theseobservations have several important implications. First, they indicatethat the lack of conventional immunodominant epitope recognition in RMvaccinated with wt RhCMV/SIV vectors is related to the prevention ofclass I MHC-restricted Ag presentation by infected cells, stronglysuggesting that the CD8+ T cell responses generated by wt RhCMV/SIVvectors are not derived via Ag-presentation by infected cells, butrather by indirect presentation. Consistent with this, these results arereminiscent of Applicants' findings with gag protein adjuvanted withpoly I:C or TLR 7/8 ligands, in which Applicants also observed thedevelopment of gag-specific CD8+ T cell responses that lack measurableresponses to the Mamu A*01-restricted gag-CM9 epitope (unpublishedobservations). However, the RhCMV vector-elicited CD8+ T cell responsesare much stronger and broader than the adjuvanted protein, suggesting ahigher degree of cross-presentation efficiency, perhaps due to dendriticcell uptake/processing of apoptotic infected cells or CMV dense bodies(Pepperl, S. et al. 2000. J Virol 74:6132-6146). Moreover, the RhCMVvector cross-presentation mechanism is notable for its apparent completeexclusion of CD8+ T cell responses to multiple, conventionalimmunodominant epitopes, suggesting the very efficient inhibition ofdirect presentation and a distinct epitope processing mechanism forindirect presentation. The second implication of these data, which ismore speculative, but potentially more significant, is the suggestionthat cytotoxicity (direct killing of SIV-infected cells) may not playthe primary role in the protection afforded by wt RhCMV/SIVvector-elicited CD8+ T cell responses. It is not that thesecross-presentation-derived responses would lack intrinsic cytotoxicfunction [the cytotoxic apparatus of CD8+ T_(EM) is present (Hansen, S.G. et al. 2009. Nat Med 15:293-299)], but rather that the epitopestargeted by these responses may not, as a group, be efficientlyprocessed and presented by infected cells, and therefore might be poortargets for the direct recognition of SIV-infected cells that isrequired for cytotoxic T cells to mediate efficient killing[particularly in light of the ability of nef to also down-regulated MHC1 molecules (Evans, D. T., and Desrosiers, R. C. 2001. Immunol Rev183:141-158]. If this is true, it further follows that the robustprotection mediated by wt RhCMV/SIV vector-elicited responses would mostlikely be due to a more indirect effector function (by T cellsstimulated by APC in the neighborhood of infected cells), such as, forexample, elaboration of CCR5 binding chemokines (Cocchi, F. et al. 1995.Science 270:1811-1815 and Arenzana-Seisdedos, F., and Parmentier, M.2006. Semin Immunol 18:387-403). S1V-specific T cell responses elicitedby the US2-11 KO RhCMV/SIV vectors clearly retain the broad epitoperecognition that arises from cross-presentation, and maintain the samephenotypic and functional capabilities of wt vector-elicited responses(not shown), but in addition, include recognition of the epitopes thatare efficiently processed by SIV-infected cells, and therefore, wouldinclude epitopes, like gag CM9 or tat SL8, that may mediate directcytotoxicity (Loffredo, J. T. et al. 2007. J Virol 81:2624-2634). Thus,the responses elicited by US2-11 KO RhCMV/SIV vectors may have enhancedanti-viral function, either by more efficient cytotoxicity or directviral suppression, or simply greater CD8+ T cell response breadth, orboth. CD8+ responses elicited by US2-11 deletant vectors might thereforemore efficiently protect RM from progressive SIV infection, increasingthe fraction of protected RM above the current level, a important goalof Applicants' efforts to optimize T_(EM) vaccine approaches.

Routine T cell response quantification is accomplished by cytokine flowcytometry (CFC; see FIG. 16) using mixes of overlapping 15 mer peptidesfor SIVgag, env, pol, and rev/nef/tat, and RhCMV IE, compared to controlpeptides (mTB Ag85b and ESAT6) and co-stimulation alone (Hansen, S. G.et al. 2009. Nat Med 15:293-299). During the vaccine phase of Group 1, 3and 4 RM, Applicants routinely follow responses to these overlappingpeptide mixes in PBMC and BAL using CFC tube #1. At necropsy, CFC tube#1 is used on fresh cell preparations from all individual tissue samplesfor all SIV proteins to comprehensively establish the systemicdistribution of the SIV-specific T cell responses. CFC tube #s 2 and 3retrospectively provide further functional characterization andphenotypic assessment (expression of CD25, HLA-DR, and PD-1) of thedegree to which the Ag-specific T cells being measured were subject toactivation in vivo. These additional “tubes” are applied in more limitedfashion, focusing on one (cryopreserved) cell preparation from eachtissue and on the dominant responses identified with the fresh tube #1analysis. Cryopreserved splenic cells (which are not limiting) areanalyzed with single peptide γ-IFN ELISPOT to “deconvolute” overall SIVprotein-specific responses into individual 15 mer peptide responses, andthen these single peptide responses are confirmed, lineage typed andfunctionally characterized with CFC tube #1 from the same cryopreservedsplenic cell preps. Responses to the 5 highest frequency (CD8) epitopesare analyzed by CFC tube #1 (and selectively tube #s 2 and 3) in alltissues to define the distribution of these individual epitoperesponses. Proliferative potential to whole protein peptide mixes and tothe 5 selected individual peptide responses per RM are determined ineach tissue by 6 day CFSE dilution cultures of PBMC and selected tissuecell preps (Onlamoon, N. et al. 2007. J Med Primatol 36:206-2), andsupernatants from these cultures are sampled after 48 hrs and analyzedfor cytokine secretion patterns by Luminex analysis (IL-2, -4, -5, -13,-17, IFN-γ, GM-CSF, TNF, MCP-1, MIP-1α/β, RANTES) (Giavedoni, L. D.2005. J Immunol Methods 301:89-101). Viral suppression assays onSIVmac239-infected autologous CD4+ T cells (Vojnov, L. et al. 2009. JVirol.) are performed on selected cell preparations to compare theanti-viral activity of responses in different tissues and arising fromdifferent vaccination routes. As demonstrated above, the CD8+ T cellresponses elicited by wt RhCMV/SIV vectors do not include the typicalimmunodominant epitopes defined for SIV or other viral vectors,precluding the use of existing tetramers to analyze wt RhCMV/SIVvector-elicited responses. However, as part of this Example and otherongoing work, Applicants may identify and determine the restricting MHCallele on common, dominant CMV/SIV vector-elicited epitopes and havetetramers constructed for the most common of these epitopes. As theybecome available, these tetramers (as well as existing tetramers for“typical” epitopes in RM likely to have suchresponses—DNA/Ad5-vaccinated and/or SIV-infected), are applied to thisExample in appropriate RM (e.g., correct MHC types), both to directlyquantify and phenotypically characterize tetramer defined responses inPBMC and tissues by flow cytometry, but more importantly, for sorting ofdefined epitope-specific populations by microarray analysis (see below).Ab responses to gag and env are quantified in plasma and rectal washingsby ELISA (Lu, X. et al. 1998. AIDS 12:1-10), with samples exhibiting envtitres >1:100 analyzed for neutralization of SIVmac239 and tissueculture-adapted SIVmac251 (Montefiori, D. C. 2005. Curr Protoc ImmunolChapter 12: Unit 12 11).

Wildtype (wt) RhCMV/SIV vectors elicit high frequency and broadlytargeted CD8+T_(EM) responses to SIV epitopes, yet do not includeresponses to the typical immunodominant epitopes targeted in SIVinfection itself or after vaccination with DNA or conventional viralvectors. Applicants have further shown that this “hole” in the wtRhCMV/SIV vector-elicited CD8+ T cell targeting is a direct result ofthe action of CMV genes in the US2-11 region that prevent MHC classI-restricted presentation by infected cells, a mechanism that mightserve CMV biology by directing CD8+ T cell responses away from epitopesmost likely to allow for efficient direct CD8+ T cell recognition ofCMV-infected cells, and therefore, efficient CD8+ T cell-mediatedcytolysis. From an HIV/SIV vaccine perspective, this remarkable biologyhas several highly significant implications, including the possibilitythat the robust, but incomplete, protection elicited by wt RhCMV/SIVvectors might be enhanced by extending CD8+ T cell targeting to epitopesthat are more efficiently processed and presented by SIV-infected cells.The addition of CD8+ T cell responses that recognize such epitopes mightimprove vaccine efficacy by increasing the efficiency of direct CD8+ Tcell recognition of SIV-infected cells, allowing for more effectivecytolysis or more accurately directed (proximate) non-cytolytic effectormechanisms (compared to indirectly presented epitopes by nearbyuninfected cells). To Applicants' knowledge, the ability to turn “off”and “on” a specific CD8+ T cell recognition pattern by simplemodification of a viral vaccine vector is unprecedented, certainly inthe SIV vaccine model, and offers a unique opportunity to define theimpact of the pattern of CD8+ recognition on the ability ofvaccine-elicited CD8+ T cell responses to suppress and perhaps evenclear primary SIV infection. Such information would clearly extendApplicants' understanding of immunologic requirements for CD8+ Tcell-mediated protection in the SIV model, but would also have a majorimpact on the translation pathway of CMV vectors into a human HIV/AIDSvaccine candidate. The finding of enhanced efficacy of US2-11 deletantvectors would provide a strong impetus to take advantage of thissuperior protection, either by steering CMV vector development towardsconstructs with this deletion and therefore targeted towards CMV-naïvepopulations (pediatric populations, almost certainly with additionalvector modifications to increase safety) or by the development ofconstructs which may present “internally processed” epitopes, yet retainthe ability to re-infect CMV-seropositive individuals (perhaps by morelimited—sub-region or specific gene—deletions in the US2-11 region).

Example 3 A Systematic Evaluation of Cytomegalovirus Vaccine Efficacy

Although human cytomegalovirus (HCMV) causes a mostly benign, unnoticedpersistent infection in immunocompetent individuals, it may causedisease in immunocompromised individuals such as transplant or AIDSpatients. HCMV is also the most frequent infectious cause of birthdefects, with an estimated 0.7% of babies in the APPLICANTS being bornwith congenital infection, and approximately 10% of these infectionsresulting in long-term sequelae (primarily sensorineural defects)(Dollard, S. C. et al. 2007. Rev Med Virol 17:355-63). The annual healthcosts to care for these children is estimated to be about $1-2 billion(Cannon, M. J., and K. F. Davis. 2005. BMC Public Health 5:70). Forthese reasons, the development of a CMV vaccine has been given highpriority by the Institute of Medicine and the National Vaccine AdvisoryCommittee (Arvin, A. M. et al. 2004. Clin Infect Dis 39:233-9). However,the development of a vaccine has been frustratingly slow despite effortsfor more than 30 years (Dekker, C. L., and A. M. Arvin. 2009. N Engl JMed 360:1250-2). A major, if not the major, road-block for CMV vaccinedevelopment is the fact that immunity from natural infection orvaccination offers only very limited, if any, protection againstre-infection by CMV (Adler, S. P. et al. 1995. J Infect Dis 171:26-32and Boppana, S. B. et al. 2001. N Engl J Med 344:1366-71). This uniquecharacteristic of CMV that prevents ‘protection from infection’ beingused as a read-out for vaccine efficacy has rendered it very difficultto evaluate candidate CMV vaccines, with current measures relyingprimarily on more subjective criteria such as reduction in diseasesymptoms (Gonczol, E., and S. Plotkin. 2001. Expert Opin Biol Ther1:401-12). The mechanism by which CMV achieves this unique ability tore-infect in the presence of pre-existing immunity has not beenunderstood until recently. Using the rhesus macaque (RM) model,Applicants' team demonstrated that rhesus CMV (RhCMV) may repeatedlyre-infect sero-positive animals even when the same strain of CMV is usedand an high level of antibody and T cell immunity is present (Hansen, S.G. et al. 2009. Nat Med 15:293-9 and Price, D. A. et al. 2008. J Immunol180:269-). In preliminary experiments Applicants further show that suchre-infection occurs with as little as 100 plaque-forming units (PFU)given subcutaneously (s.c.). Remarkably, re-infection of sero-positiveanimals is prevented when Applicants use a RhCMV recombinant (designatedΔRh182-9) that has lost its ability to prevent antigen presentation bymajor histocompatibility complex class I (MHC-I) due to deletion of theRhCMV homologues of the US6 family of HCMV immunevasins, US2-US11.Depletion of CD8⁺ T cells restores the ability of ΔRh182-9 to re-infectsero-positive RMs, showing that inhibition of antigen presentation isone of the underlying reasons for re-infection.

Importantly, the capacity of immunity induced by natural CMV infectionto protect against the US2-11 deleted virus ΔRh182-9 is thus anexcellent measure for the quality of the CD8⁺ T cell response againstCMV induced naturally by prior infection or artificially by vaccination.This measure far surpasses all other means currently available tomonitor CMV vaccine efficacy, since it is effectively ‘all-or-none’:once the sites of persistence have been reached by ΔRh182-9 (even by afew viruses) long-term infection and easily detectable levels of viralshedding occur. In contrast, other measures such as viremia and clinicalsigns of infection are notoriously variable, subjective, and areespecially problematic where vaccine effects are rather subtle.Applicants therefore propose to use protection against ΔRh182-9 tosystematically re-evaluate some of the basic assumptions regardingvaccine approaches that have been made over the years regarding CMVvaccines. This allows Applicants to develop empirically basedrecommendations for the best strategy to develop a vaccine against HCMV.To accelerate future development of HCMV-based vaccines Applicants alsogenerate and characterize in vitro recombinant HCMVs containing the sameattenuating genetic disruptions present in the attenuated RhCMVvaccines.

Applicants' recent findings using a RhCMV virus deleted for the US2-11genes (ΔRh182-9) show that this family of immune evasion genes isresponsible for the ability of CMV to re-infect the healthysero-positive host. Applicants' subsequent observation that CD8⁺depletion prior to challenge overcomes the block to ΔRh182-9 infectionin CMV sero-positive animals shows that the US6 family proteins functionby their effect on the CMV-specific CD8⁺ T cell response. Thus, ΔRh182-9infection may serve as an all-or-none read-out for whether aCMV-specific CD8⁺ T cell immune response is functionally comparable tothat induced by natural WT CMV infection.

CMV possesses the remarkable ability to re-infect and establish apersistent infection regardless of host CMV immunity (Boppana, S. B. etal. 1999. Pediatrics 104:55-60, Farroway, L. N. et al. 2005. EpidemiolInfect 133:701-10 and Hansen, S. G. et al. 2009. Nat Med 15:293-9) (FIG.31). After initial infection, CMV is shed for years from epithelialsurfaces into body fluids (saliva, tears, urine, genital secretions andbreast milk), and transmission generally involves mucosal exposure tosuch fluids, most commonly in early childhood or adolescence (Boppana,S. B. et al. 1999. Pediatrics 104:55-60 and Pass, R. F. 2001.Cytomegalovirus, p. 2675-2705. In P. M. H. David M. Knipe, Diane E.Griffin, Robert A. Lamb Malcolm A. Martin, Bernard Roizman and StephenE. Straus (ed.), Fields Virology, 4th ed. Lippincott Williams & Wilkins,Philadelphia). In humans, the inability of natural HCMV immunity toprotect against re-infection was initially demonstrated in an earlyhuman vaccine trial, wherein re-infection using low doses of areplicating HCMV strain, Toledo-1, was observed in healthy HCMVsero-positives (Plotkin, S. A. et al. 1989. J Infect Dis 159:860-5 andQuinnan, G. V. et al. 1984 Ann Intern Med 101:478-83). Evidence forre-infection and virus persistence was observed by virus isolation fromone individual (10 pfu group), and induction of an amnestic anti-HCMVantibody response in a second individual (100 pfu group)—although noindividuals receiving doses of either 10 (n=2), or 100 pfu (n=5) showedany HCMV-associated symptoms. All individuals in a third sero-positivegroup that received 1,000 pfu of Toledo-1 (n=5) showed evidence ofinfection, comprised of an amnestic HCMV-specific antibody and T cellresponse. Virus was also detected in throat swabs and urine from onesymptomatically infected individual, and in the blood from a secondasymptomatic individual. Toledo-1 was administered via a parenteral(subcutaneous) route, and it is possible that protection against naturalinfection via mucosal routes may by impacted by HCMV immunity (Adler, S.P. et al. 1995. J Infect Dis 171:26-32). However, a study performed in acohort of 46 HCMV sero-positive pregnant women using CMV strain-specificantibodies as an indicator of re-infection suggests that natural HCMVre-infection of the sero-positive healthy adult is a common occurrence(Boppana, S. B. et al. 2001. N Engl J Med 344:1366-71).

In contrast to the limited effect of HCMV-induced immunity on preventingre-infection, maternal HCMV immunity reduces both transmission of HCMVto the fetus (Fowler, K. B. et al. 2003. JAMA 289:1008-11), as well asthe occurrence of disease following infection in congenitally-infectedinfants (Fowler, K. B. et al. 1992. N Engl J Med 326:663-7 and Ross, S.A. et al. 2006. J Pediatr 148:332-6). In an initial study by Fowler etal (Fowler, K. B. et al. 2003. JAMA 289:1008-11), maternal HCMVsero-positivity corresponded to a 70% reduction in the risk ofcongenital HCMV infection. A more recent exhaustive meta-analysis,analyzing results from epidemiologic studies published between 1966 and2006 showed the rate of congenital HCMV transmission to be 1.4% comparedto 32% in HCMV sero-positive and sero-negative mothers, respectively(Keenan, R. J. et al. 1991. Transplantation 51:433-8). The impact ofmaternal HCMV sero-status on disease outcome of congenital infection hasnot been as thoroughly explored. However, the existing evidence suggeststhat maternal HCMV sero-positivity reduces the severity of congenitaldisease (Fowler, K. B. et al. 1992. N Engl J Med 326:663-7 and Ross, S.A. et al. 2006. J Pediatr 148:332-6). In one study, the incidence ofsymptomatic disease was 25% compared to 8% in congenitally infectedinfants from primary and recurrently infected mothers, respectively(Fowler, K. B. et al. 1992. N Engl J Med 326:663-7). In a second study,although the frequency of hearing loss was comparable incongenitally-infected infants following primary or recurrent infection,the severity of the hearing deficit was greater in congenitally infectedinfants following maternal primary infection (Ross, S. A. et al. 2006. JPediatr 148:332-6). Both humoral and cellular CMV-specific responsesappear to play a role in reducing transmission (for review, see (Adler,S. P. 2008. J Clin Virol 41:231-6)). This importance of CMV-specific Tcell responses is most clearly shown by the increased incidence of CMVtransmission to the fetus in mothers with T cell deficiency from AIDS(Adler, S. P. 2008. J Clin Virol 41:231-6 and Doyle, M. et al. 1996.Pediatr Infect Dis J 15:1102-6). Together, these studies suggest that arealistic goal of an HCMV vaccine is to reduce the incidence andseverity of congenital CMV disease.

The poor efficacy of any vaccine approach tested to date is consistentwith the inability of natural CMV immunity to protect from re-infection.The greatest level of protection for any HCMV human vaccine trial wasrecently observed using a recombinantly-expressed HCMV envelope gB withMF59 adjuvant-based approach in a placebo-controlled clinical trial(Pass, R. F. et al. 2009. N Engl J Med 360:1191-9). However, thedifference in protection between vaccinees and saline controls was lessthan two-fold (7.7% compared to 13.5% in saline control group), was notrobust as incorrect assignment of a small number of subjects could haveeliminated statistical significance, and although a trend towards aneffect on congenital infection was suggested (1 case of congenitalinfection, compared to 3 cases in saline control group; note after studystopped 2 additional congenital infections in saline group), thisdifference was not statistically significant. Based on the level ofprotection afforded in this study, it was estimated that a studyadopting symptomatic congenital infection as an endpoint would requireenrollment of >50,000 women (Dekker, C. L., and A. M. Arvin. 2009. NEngl J Med 360:1250-2). The lack of any statistically significant immunecorrelate with protection of the fetus, and the necessarily rigoroussafety restrictions of vaccine trials performed in women of reproductiveage are further concerns that are essentially prohibitive to anythorough analysis of HCMV vaccine candidates designed to interruptmaternal to fetal transmission of CMV.

In summary, although immunity induced by natural WT CMV infection isunable to protect against re-infection, it does afford a significantlevel of protection against congenital infection and severity ofdisease. This observation would suggest that a vaccine that may safelyinduce a level of immunity comparable to that induced by WT CMVinfection may have a significant impact on congenital infection. Thenecessarily strict safety restrictions for analysis of candidate CMVvaccines in this target population (i.e., CMV sero-negative women ofchild bearing age, and sero-negative pregnant women), pose significantproblems for vaccine development, and probably preclude the use of anyapproach but a fully replication-defective based strategy. Thislimitation of human vaccine trials leaves unanswered the criticalquestion of what level of vaccine attenuation may be achieved whilststill inducing a level of immunity comparable to that acquired throughnatural CMV infection (i.e., an immunity that may decrease congenitalinfection). Currently, a non-human primate model to study CMV maternalto fetal transmission does not exist, and the genetically divergentrodent models do not completely translate to human HCMV infection. Inthis Example, Applicants propose that use of a dual-challenge strategycombining a) the all-or-none read-out of ΔRh182-9 challenge, with b) thecontinuous variable of viremia following WT-RhCMV s.c. challenge, areable to determine the minimal requirements for induction of aCMV-specific immunity that functionally recapitulates immunity inducedby WT CMV infection. The biochemical comparison for these attenuatedRhCMVs in parallel with their HCMV counterparts containing the identicalgenetic lesion ensure that any attenuated RhCMV showing protection maybe translated into the HCMV ‘strain of choice’ with the confidence thatthe genetic deletion results in an HCMV vaccine with a comparablebiochemical phenotype.

There is ample evidence that re-infection occurs in HCMV (Boppana, S. B.et al. 2001. N Engl J Med 344:1366-71 and Ross, S. A. et al. 2006. JPediatr 148:332-6). In the RM model Applicants previously showed thatCMV-positive RMs could be repeatedly re-infected with 10⁷ plaque formingunits (PFU) of recombinant RhCMV (Hansen, S. G. et al. 2009. Nat Med15:293-9). Each re-infection was detected as a boost in the anti-CMV Tcell response and by the development of a de novo response to a new SIVantigen marker present only in the re-infecting virus. To determinewhether re-infection also occurs at lower doses of RhCMV, Applicantsinfected sero-positive RMs with decreasing titers of RhCMV expressingSIV Gag (RhCMV-Gag). Re-infection was followed immunologically bymeasuring SIV Gag-specific T cell responses (Hansen, S. G. et al. 2009.Nat Med 15:293-9). When sero-positive animals were inoculated s.c. with10⁴ or 10² PFU of RhCMV-Gag a significant Gag-specific T cell responsewas observed at 14 days post-infection (p.i.) (FIG. 31). ThisGag-specific response remained detectable for the duration of theexperiment. Based on Applicants' experience in comparable studies, Gagresponses are detectable for the life of the animal (>7 years p.i.)indicating a long-term persistent infection.

To determine whether Gag-expressing virus was shed by infected animals,Applicants sampled saliva and urine on a weekly basis. Upon co-culturingvirus pellets with RM fibroblasts (RFs), Applicants monitored Gagexpression in immunoblots. In animals that received 10⁷ PFU ofRhCMV-Gag, Applicants detected Gag-positive virus in the urine of someanimals within 7-14 days p.i., and in all animals by 42 days p.i.Similarly, buccal swabs of all animals were positive by 70 days p.i.Animals inoculated with lower doses had a trend toward longer time p.i.before detection of RhCMV-Gag in saliva and urine, but all animals wereeventually positive. Consistent with previous published studies for HCMV(Plotkin, S. A. et al. 1989. J Infect Dis 159:860-5 and Quinnan, G. V.et al. 1984. Ann Intern Med 101:478-83), these data show that priorinfection by RhCMV does not protect against re-infection, even at CMVdoses as low as 100 PFU. These results also indicate that the de novoimmune response against a foreign antigen is a more sensitive andreproducible indicator of CMV re-infection than the detection of virusin the secretions.

The ease with which RhCMV overcomes a substantial, pre-existing anti-CMVimmune response during re-infection suggests that CMV has evolvedmechanisms to evade host immune surveillance. The adaptive cellularimmune response is known to be particularly important for controllingCMV. In humans, CMV-specific T cells comprise on average approximately10% of both the CD4⁺ and CD8⁺ memory compartments (Sylwester, A. W. etal. 2005. J Exp Med 202:673-85) suggesting that enormous resources areconstantly devoted to controlling this virus. Applicants hypothesizedthat a key aspect of re-infection might be the ability of CMV to escapeT cell detection. All CMVs are known to encode multiple proteins thatprevent antigen presentation by MHC-I, thus limiting the ability of CD8⁺T cells to recognize and eliminate CMV-infected cells (Loenen, W. A. etal. 2001. Semin Immunol 13:41-9). Applicants previously demonstratedthat the RhCMV genomic region Rh182-Rh189 encodes functional homologuesof the US2, US3, US6 and US11 immunevasins of HCMV (Pande, N. T. et al.2005. J Virol 79:5786-98). To determine whether these viral inhibitorsof antigen presentation were required for re-infection, Applicantsreplaced the Rh182-189 region with an expression cassette for the SIVGag antigen, which allowed Applicants to monitor Gag-specific immuneresponses in infected animals (virus designated ΔRh182-9Gag). Deletionof the Rh182-9 region was confirmed by PCR and Southern Blot. Applicantsfurther monitored in vitro growth in primary RFs and observed nodifference to WT, BAC-derived RhCMV (data not shown). Initially,Applicants determined whether ΔRh182-9Gag would be able to establishpersistent infection in CMV-negative animals. Applicants infected twosero-negative animals with 5×10⁶ PFU of ΔRh182-9Gag and two controlanimals with the RhCMV-Gag (Hansen, S. G. et al. 2009. Nat Med15:293-9). Infection was monitored immunologically by the development ofa CMV-specific and SIV Gag-specific immune responses and virologicallyby viral shedding of Gag-marked viruses into the urine and saliva. Asshown in FIG. 32, a Gag-specific T cell response to ΔRh182-9Gag wasdetectable with similar kinetics and magnitude as responses againstRhCMV-Gag. Moreover, ΔRh182-9Gag (confirmed by immunoblot) was detectedin the secretions of the infected animals even >1 year p.i. (data notshown). Therefore, Applicants conclude that ΔRh182-9Gag is competent toestablish persistent infection in CMV-naïve animals.

To determine whether ΔRh182-9Gag would be able to re-infectsero-positive animals Applicants inoculated CMV⁺ RMs s.c. with 10⁷ PFU.Consistent with Applicants' previous observations, the WT controlRhCMV-Gag re-infected all four animals as evidenced by detection of SIVGag-specific T cell responses in bronchoalveolar lavage (BAL) andperipheral blood mononuclear cells (PBMC) (FIG. 33A). In contrast, noneof the four animals infected with ΔRh182-9Gag displayed any detectablesigns of re-infection either by T cell assay (FIG. 33B) or by monitoringsecretions for virus (data not shown). This lack of re-infection was notdue to these animals being refractory to re-infection as the sameanimals could be re-infected with ΔRh178Gag, a virus that lacks aRhCMV-specific MHC-I evasion gene that has no HCMV counterpart (Powers,C. J., and K. Fruh. 2008. PLoS Pathog 4:e1000150) (FIG. 33C). Together,these experiments suggest that inhibition of antigen presentation by theUS6 family (US2-11 genes) of immunomodulators is essential for RhCMVre-infection of the sero-positive host.

Since ΔRh182-9Gag was able to infect CMV-naïve animals, but notCMV-positive animals, Applicants hypothesized that the CMV-specificimmune response, and particularly the CD8⁺ T cell response, preventedre-infection by the “immunologically defenseless” ΔRh182-9Gag virus. Totest this hypothesis Applicants immuno-depleted CD8⁺ T cells fromsero-positive RMs prior to re-infection with ΔRh182-9Gag. Serialinjections of antibody cM-T807 (Schmitz, J. E. et al. 1999. Science283:857-60) temporarily reduced CD8⁺ T cells for the duration ofapproximately 2-3 weeks (FIG. 34A). All four CMV-positive,immuno-depleted animals were re-infected by ΔRh182-9Gag as shown by SIVGag-specific CD4⁺ T cell responses which were observed at 7 days p.i.(FIG. 34B). Interestingly, the animals even generated Gag-specific CD8⁺T cell responses when CD8⁺ levels rebounded. Moreover, both CD4⁺ andCD8⁺ T cells were detectable for the remainder of the experimentsuggesting that a persistent infection had been established. Applicantsare currently examining secretions by co-culture for presence ofΔRh182-9Gag. Applicants conclude that CMV-encoded immunevasins enablere-infection of the sero-positive host due to their ability to evade thehost CMV-specific CD8⁺ T response. However, immunity induced by naturalCMV infection is able to protect against CMV re-infection in the absenceof these virally encoded immunevasins.

For the first time, Applicants' data establish a clear causalrelationship between viral immune modulation (by immunevasins) and theunique ability of CMV to re-infect the sero-positive host. Given theclose evolutionary relationship between the humans and RMs, as well asthe functional conservation of US2, 3, 6 and 11 between HCMV and RhCMV,Applicants consider it highly likely that the ability of HCMV tore-infect humans is also mediated by inhibitors of antigen presentation.These observations also have another implication that is highly relevantto the goal of vaccine development. Specifically, this is the first timethat CMV-specific immunity in a primate species has been shown tocompletely prevent re-infection by CMV, even at a very high doses ofchallenge virus. Applicants therefore conclude that protection againstΔRh182-9 is an all-or-none measure for the quality of the pre-existingCMV specific immune response.

Thus, challenge with ΔRh182-9Gag may be used to determine whether anytype of vaccination effort has successfully generated a CD8⁺ T cellresponse that is as protective as that induced by natural infection.Applicants anticipate that this assay is far superior to any othermeasure of CMV-vaccine efficacy, since this all-or-nothing read-outallows candidate vaccine efficacy to be determined using relativelysmall groups of animals. Using ΔRh182-9Gag challenge, Applicantsre-examine whether non-replicating, partially replicating ornon-replicating heterologous ‘prime-boost’ vaccines are able to induce aprotective response.

Given the clear demonstration that HCMV re-infection of the fully immunehost may efficiently occur even at low doses of virus, it seems thatcomplete prevention of infection in vaccinees is likely notrealistically an achievable goal. However, substantial epidemiologicaldata shows that CMV immunity afforded by natural CMV infectionsignificantly decreases maternal to fetal transmission of CMV. Thus, areasonable and achievable goal for a CMV vaccine is to develop a vaccinethat mimics immunity induced by primary infection, and thereby reducestransmission of CMV from the mother to the fetus (Adler, S. P. et al.1995. J Infect Dis 171:26-32). Such a vaccine has to be extremely safesince the target population includes pregnant women. Finding an optimalbalance between safety and efficacy has been a major obstacle in CMVvaccine development. This is, in large part, because the unique abilityof CMV to re-infect CMV-immune individuals renders it difficult, if notimpossible, to use protection from infection as a final read-out (atleast in closely related primate models). For this reason, a majorunsolved question is at what level of attenuation a vaccine stillinduces a level of immunity comparable to natural CMV infection, andthereby achieve the maximal level of “protective” efficacy realisticallyachievable. Applicants' goal is to address this critical question, anddetermine the level of attenuation of CMV at which an immune responseequivalent to natural immunity is still generated. Applicants addressthis question in the RhCMV/RM infection model—a model that closelymimics HCMV infection in humans, but that permits empirical‘fine-tuning’ of the level of CMV attenuation. In the first approach,Applicants address the question of whether replication-deficientCMV-based vaccines, either single- or low-cycle, are sufficient toinduce a CMV-specific immune response and, following the induction of animmune response, what are the characteristics of immunity, regardingduration, magnitude and T cell phenotype. In a separate approach,Applicants introduce an on/off switch into the RhCMV genome which allowApplicants to inhibit or re-start viral replication at any time afterinfection thus addressing the roles of initial virus dissemination tosites of latent/persistent infection in the host, as well as of acuteversus persistent replication in inducing a CMV-specific immuneresponse. To overcome the problem in measuring efficacy of the immuneresponse induced by the various attenuation strategies, Applicantspropose to use the ability of a vaccine to protect against the US2-11deleted recombinant virus ΔRh1829Gag. In addition to the attenuatedvaccines, Applicants also evaluate the ability of ‘Prime-Boost’ vaccines(IE-1, pp65b, gB) to prevent ΔRh182-9Gag re-infection using a DNAprime/adenovirus boost strategy. Vaccinated animals that were protectedagainst ΔRh182-9Gag are further challenged with WT-RhCMV followed bymonitoring of viremia. Applicants anticipate that this dual-challengestrategy show that protection against re-infection with ΔRh182-9Gagcorrelates with the ability of a vaccine to reduce WT-RhCMV viremia, amuch more difficult to monitor and variable read-out currently used toevaluate vaccine efficacy. Protection against ΔRh182-9Gag thus indicatethat a given vaccine was able to generate a CMV-specific immuneresponse, particularly a CD8⁺ T cell response, similar to that inducedduring natural infection. One of the great advantages of the RhCMV modelis the close evolutionary relationship between the human and rhesusCMVs, and their respective hosts. Therefore, Applicants in parallelgenerate and characterize HCMV-derived constructs containing identicalgenetic deletions thereby ensuring that any of the attenuated vaccinesthat shows promise in the RhCMV system is functionally comparable to itsHCMV counterpart. Applicants anticipate that results obtained in thisproject are directly transferable to development of an HCMV-basedvaccine candidate.

Example 4 A US2-11-Deleted Virus May be Used as a Testing Device forCMV-Vaccine Efficacy

Applicants have infected rhesus macaques with RhCMV lacking the geneRh110 that encodes for the viral transactivator pp71. RhCMVΔRh110 isgrowth-deficient in vitro but is not secreted from infected monkeys.Applicants have tested whether monkeys infected with RhCMVΔRh110 areprotected against challenge with RhCMVΔUS2-11 expressing the SIV antigenGag. Protection was demonstrated by the absence of a boost inRhCMV-specific T cell responses. In contrast, monkeys infected withwildtype-virus show a boost of the CMV-specific T cell response (seeFIG. 23). This result indicates that spread-deficient CMV is capable ofinducing a T cell response that protects against challenge with US2-11deleted virus. This result also indicates that a US2-11 deleted virusmay be used to monitor the efficacy of the T cell response.

In a similar experiment Applicants created a RhCMV lacking the tegumentproteins pp65a and pp65b encoded by the genes Rh111 and Rh112,respectively (see FIG. 24). These proteins are not required for viralgrowth in vitro. However, pp65 is an immunodominant protein that isincluded in current formulations of subunit vaccines for CMV developedby various investigators. To examine whether pp65-specific T cells arerequired for protection against challenge with ΔUS2-11, Applicantsinfected rhesus macaques with RhCMVΔRh111-112. As expected Applicantsobserved an immune response against the IE-proteins of CMV, but notagainst pp65. In contrast, a pp65-specific T cell response was readilydetected in animals infected with RhCMV (blue line). Applicants alsoobserved that RhCMVΔRh111-112 is secreted from infected animals.

Having thus described in detail preferred embodiments of the presentinvention, it is to be understood that the invention defined by theabove paragraphs is not to be limited to particular details set forth inthe above description as many apparent variations thereof are possiblewithout departing from the spirit or scope of the present invention.

What is claimed is:
 1. A method of determining efficacy of a CMVvaccine, comprising (a) administering a CMV vaccine to a test subject,(b) challenging the test subject with a CMV vector, wherein theglycoproteins within the US2 to US11 region of CMV are deleted from theCMV vector, and wherein the CMV vector contains and expresses at leastone immunogen of the CMV vaccine, and (c) measuring a CD8+ T cellresponse, wherein the CMV vaccine in efficacious if a CD8+ T cellresponse is protective against the challenge with the CMV vector lackingthe glycoproteins within the US2 to US11 region of CMV and wherein theCMV vector contains and expresses at least one immunogen of the CMVvaccine.
 2. The method of claim 1, wherein the CMV vaccine lacks thetransactivator pp71.
 3. The method of claim 1, wherein the CMV vaccinelacks the tegument protein pp65.